14 Replies Latest reply on Oct 11, 2017 3:15 AM by spikeypup

    Can not set 75Hz on 75Hz monitor (rx480, latest driver)

    purple_rain

      Just received new monitor Dell S2418HN for my MSI RX480 GAMING X 8G (latest driver 17.9.3 installed).

      Monitor is connected via HDMI 2.0. 1920x1080 at 75Hz and Freesync are supported by this monitor model.

      But i can't get it to perform at 75Hz! Windows and AMD Crimson Driver are showing 59Hz and not let me change it to 75Hz.

      OS is Windows 10 x64

      Latest monitor driver and Dell software are also installed.

       

      So the question is - where and how to set refresh rate to 75Hz?

      I always thought GPUs can automatically detect max frequency from monitor and set it initially...

        • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
          spikeypup

          Hiya purple_rain!

           

          You are correct, most of the time the video card will detect the proper settings, this is all based on something called EDID, which is a small kind of PROM/NVRAM that is programmed on the display's interface(s) to relay to the video card what the proper timings and features of the monitor are, such as deep color, 10-bit support, what Hz and at what resolutions it can display, etc.

           

          Sometimes this process doesn't work out correctly however, and sometimes the EDID chips are bad, even with fresh monitors.  Not to worry, there are ways to fix this, such as with the Custom Resolution tool in Crimson drivers on the Display Page, or with a utility like CRU (Custom Resolution Utility), which is what I use to overclock all 3 of my displays, 2 on HDMI and one on DP-->DVI.  I have them all set to 70hz even though they are spec'd to 60hz in fact my Benq can reach 95hz!, my Asus only 75hz sadly, and my Dell can go about 85hz.  But I settled on 70hz as that is kind of at the point where you can't tell the difference too much until like 100hz.  Anyway, I'm digressing.

           

          First things first, I checked the specs on that monitor, at 1920x1080P, it is 60hz, the 75hz is more than likely for 1280x720 or 1280x1024, which is common, it (the OS and most software) reports the MAX REFRESH rate of the monitor, regardless of the resolution.  This is a common misunderstanding and sometimes manufacturers will use this to mislead people, in this case, everything is correct and no sneaky act was done.

           

          Now, it MIGHT be possible to overclock this monitor to 75Hz, I don't know, and the process of manipulating timings and pixel clock to achieve the desired Hz (In crimson they refer to this as G. Hz, as you'll see when you click on "specs").  However, sometimes it is not so hard.  In this case you lucked out, the specs in the manual give you the timings that you will need to get your monitor to 75hz @ 1080P.  See the chart below:

          Using the custom resolution utility in Crimson, you can create a CR for that display , using the second 1920x1080 listing (closest to the bottom), to achieve 75hz you will need to manually adjust the pixel clock to 174.5Mhz, and adjust your Horizontial polarity to positive, and your vertical to negative as shown in the table, that is important because the standard 60hz runs at pos/pos, then you should set the G. Hz to 75, and it should change the horizontal frequency accordingly, in fact if you change the polarity first, then do the G.hz to 75hz, the pixel clock should set itself to 174.50 in the window, and the horizontal will self adjust as well.  If it doesn't you will need to make the manual changes.

           

          I prefer to use CRU to create EDID overrides in windows itself, because of the way WDDM 2.0 works and sets up display configurations, it can actually cause your monitor to change to the default 60hz setting quite often, when certain apps or games go full screen for instance, many times windows will call up the 60hz setting, the only way to bypass this from happening is two steps, delete all excess enumerated displays, and then override the EDID with the setting you want at 75hz, I personally remove the 60hz defaults from my EDID and leave only my 70hz settings on all my displays, this prevents the OS from allowing the shift to the 60hz settings.

           

          I've attached the CRU utility in a ZIP file, and I created an EDID for you based off the specs that Dell provides, and it should work.  But perform this at your own risk, while this should be no problem, I cannot take responsibility if something goes wrong.  In the event that a change results on the monitor being funky or distorted you should still be able to see well enough to use the "reset-all" file that is included, this will reset all the monitors to default after a reboot, so you should be ok if something does not work out.  Now when you open the CRU utility, ensure that you OPEN it as ADMINISTRATOR if it doesn't do it automatically, I can't remember, so just right click it and select Open/Run as Administrator.  Once open you'll have a dropdown that features all the monitors enumerated for your system, with an indicator that says <active> for the one that is currently in use, all the others are garbage and you should delete them, see the picture below:

          Once you click OK, don't expect anything to happen, because you either need to restart your computer, or do what I think is better, because if you restart chances are windows will re-enumerate the monitor based on the EDID and not the override and your monitor will spontaneously change from 75 to 60 all the time.  So instead I open Relive and simply go to Displays, and you can do one of two things, either enable GPU scaling, then Disable it a few seconds after it's done, or you can change your pixel format and change it back, you probably should use RGB FULL 4:4:4, it may be set to LIMITED, so click Full and then it will change, and once done, you can leave it there, if it is already on RGB Full, then select LIMITED, and then change it back to FULL, give it a few seconds before you do it, don't do it too fast, it can cause a crash.  Once you do this, the EDID override will be recognized by the GPU and Windows, and you don't have to restart your PC at all, and best of all Windows won't re-enumerate the display, which guarantees that the EDID I made with only the 75Hz at 1080P will be used and thus will also provide Vsync at 75hz in windows, and within games should you choose to use it.  I setup the freesync range for 29-75hz, as the specs don't really say what it is, so I'm just guessing on that, it is possible that it may be different.  Note that the Gaming HDR mode in the monitor settings will DISABLE Freesync, as they are not compatible.

           

          I'm hoping this works for you, typically this process is very trial and error and takes time, you should google Custom Resolution Utility and you'll find more complete guides as to the usage, I just did this for you in the hopes that it works and you don't have to worry about it, but it may not work at all, fingers crossed!  Again although the risks are very minimal if any, you are doing this at your own risk, I nor AMD are responsible for your CRU/EDID modification experience.

           

          Let me know how it goes!

           

          Spikeypup

          2 of 2 people found this helpful
          • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
            bearcat22

            According to the manual your monitor only supports 1920 x 1080 at 60 hz

            1 of 2 people found this helpful
            • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
              kingfish

              "Max Reported rate" does not mean your monitor will support it.

                • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                  spikeypup

                  Absolutely correct, and I hate the way windows OLD A$$ XP display window, yes it's the same applet, shows the MAX reported rate, but fails to mention it is some lame low resolution.  In this case, digging into the manual, there are in fact timings that will support 1920x1080 @ 75Hz, but an EDID override or Custom Resolution in Crimson will be necessary.

                   

                  It's hilarious, it took me so long to write that post that you guys had already replied, I got to it originally 2 minutes after posting, and then god knows how long later...finally my reply was finished, lol then I lol'd when I saw you guys had already posted.  You guys rock! kingfish bearcat22

                • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                  purple_rain

                  Hi spikeypup!

                  Big thanks for such a perfect and useful answer. It’s really awesome when people write answers like this! Appreciate this.

                  But after all I’v managed to get my new monitor work normally at 75 Hz with freesync (it’s totally supported on this display despite some opinions in this thread).

                  It turned out that my TV caused this mess. TV is connected in duplicate screen mode to my GPU. I think AMD drivers and Windows somehow did not let me go over 60Hz cause TV max support frequency is 60 Hz.

                  I plugged of TV, plugged monitor into TV’s port, reset settings and voila – it allowed me to set 75Hz in Windows!

                  After that there was pretty buggy story with plugging TV back to GPU and configuring it as secondary duplicate screen, but I’ve managed to solve this quest.

                  Now Dell monitor works with freesync at 1920x1080 75Hz Full RGB and TV duplicates it with 1920x1080 60Hz Ybrr 4:4:4.

                  So everything came to normal)

                  Thanks!

                    • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                      spikeypup

                      TLDR:  This is just a rant about why displays sometimes change their own refresh or change their display ID number, etc.  Ranty reading

                       

                      Purple_rain,

                       

                      That is wonderful news!  Yeah I'd like to blame that one on WDDM and Windows, when you have varying displays and especially with different refresh rates, oh the mysterious things that will happen.  Especially if you mix things like native display port (no dongles attached), HDMI and VGA and DVI together, because things like Power Management and stuff function fundamentally different it can sometimes effect enumeration or connection of the display itself, and then Windows likes to see it as "Oh this is a whole new setup, never seen this before..."; even though it hasn't changed at all, and then you end up with a monitor that keeps changing itself from 60 to 50hz or 60 to 59hz. 

                       

                      I mean there is a lot more to it than that and I'm over simplifying, from a technical PHY/protocol view windows is doing what theoretically makes sense, but as I've said before the problems within WDDM in matters such as this are they are not practical to almost everyone's everyday experience.  Some of the behaviors of WDDM would make it seem to me that they believe there are users out there changing displays and moving them around, or their PC... on a daily basis.  While this may be somewhat true for Laptop users, it also kind of isn't. 

                       

                      I've been a road-warrior for like 20 years, and gave many presentations at many offices etc.; and  I almost always had my own projector or displays, or if I was connecting to a foreign unit, it was typically on a repeat basis.  When I was at the office or home, those display scenarios always stayed the same, in terms of display type/mfg. and positioning (relative location/position of display on desk in a multi-monitor scenario); it almost never changed for the lifetime of the laptop.  As for desktops, I don't know about you, but I don't find myself moving my displays around or changing them very often, if at all during the lifetime of my system, in fact my display setup usually outlives my PC, never changing once in it's configuration, model(s), or layout.

                       

                      So I bring all that up because the way Windows handles displays and enumerates them is really kind of stupid in my opinion and from having to solve and answer so many issues related to the way it handles said displays justifies my position on it.  The idea was that windows would remember the varying specifics of your display setup relational to the desktop (let's just call it a canvas) and how it is comprised, including display models, which GPU path/port it's on, resolutions, and refreshes.  So every time you install a display and set it up, windows would remember exactly how you had it and bring up that configuration.  In a perfect world that sounds nice, but the world ain't so perfect.  Some things that throw off Display Designation or Enumeration: 1. Often some changes in drivers necessitate changes around the WDDM model causing ports to change designation, sometimes people do move their displays and swap one cable for the other. 2. Some game engines will force a refresh rate or resolution change upon full-screen startup, etc. etc.  Well... often times that is interpreted by the display subsystem as a change to the desktop composition, or how the canvas is comprised, so, it enumerates displays, makes a new configuration, designates and enumerates that configuration and then you end up with strange things like refresh rates that change and don't go back to their original setting (because it thinks you have this "new" setup/configuration of displays)  etc. many times because of a lot of tiny factors to be honest and some of it just down to timing or order of events.

                       

                      Over time, especially if you have had multiple video cards and have a few displays and changed a couple here and there or moved some plugs, it is not uncommon for me to see 30,40,50,even hundreds in some people's cases of enumerated desktop compositions (canvas configurations) in their registry.  Sometimes it is because of the way the display offers itself up as well, there are just many factors.  And then that's when the weirdness really happens, you move one monitor here, but it seems to stay over there, then the number designation in the control panel changes, but then it's referred to as a different display number elsewhere, etc.  So long story very short because I just realized I'm rambling as per usual, it was a great idea, but a failure in practice in my opinion,  as it often leads to more people's displays NOT doing what they want or intend and DOING stuff they definitely don't want.  I've never once heard a client or friend say "Wow Windows did a great job remembering my display layout!" and that's not because it's one of those out of sight out of mind things, it's because they're busy saying, "DUDE, WTF is wrong with this piece of crap and why are my displays changing refreshes and number and why are options disappearing!", I hear the latter 100% of the time, and the former 0% of the time. 

                       

                      My solution, like I said above, I use CRU to remove any potential for bad situations by locking in what I want for refreshes and at what resolutions, and I eliminate all extra enumerated displays from the registry manually, especially the MSBD Renderer attached enumerated displays (while one always remains or will be enumerated when necessary such as pre-full-boot situations like O/S selection or safe-mode when the standard driver cannot provide for it).  Now my refresh rates always stay the same across all my displays, and no matter what  I do in a game or other full-screen app, when I return to the desktop, it is exactly as I left it.  Of course though, after upgrading drivers or if I change displays or connected ports, I have to go through and clean everything out again to ensure it stays how I like it, but I have it down to a science and it only takes a couple minutes at best.

                       

                      Ok so my friend is nagging at me about this long reply and how I'm probably boring everyone to death... so now I must bid you ta ta! 

                       

                      Cheers!

                       

                      Spikeypup

                      • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                        kingfish

                        If you would have furnished the info that was requested....INFORMATION REQUIRED WHEN POSTING A QUESTION

                        • Display Devices
                          • Make and model, connection/adapter in use, resolution and refresh rate; e.g. Samsung UE32850R 3840x2160 @60Hz Active DP to HDMI adapter
                          • One line for each display device connected

                         

                        "But after all I’v managed to get my new monitor work normally at 75 Hz with freesync (it’s totally supported on this display despite some opinions in this thread).

                        It turned out that my TV caused this mess. TV is connected in duplicate screen mode to my GPU. I think AMD drivers and Windows somehow did not let me go over 60Hz cause TV max support frequency is 60 Hz."

                      • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                        revoc

                        I have this problem. Curiously, it only goes down to 60hz (the option for 75hz disappears in the Windows dropdown menu) when I have GPU Scaling enabled in the drivers. When GPU Scaling is disabled, 75hz works fine. This proves that my monitor is 75hz capable, that the monitor and hardware connections are fine, and suggests the problem lies with AMD's drivers. Does anyone have any thoughts or inputs on this? It would be nice to have GPU Scaling on and be able to use my monitor to it's fullest capabilities.

                          • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                            spikeypup

                            Hi revoc,

                             

                            Can you please include some information about your system, such as GPU, Monitor Model and Brand, Connection Method, and under "Display" can you please take a snippet/screenshot of the "specs" page for the display in question, do one for when GPU scaling is on, and when one is off.  I know it may seem to be within the drivers, but I believe this is more of a WDDM problem, but we'll see, either way I will help you the best I can.

                             

                            Thanks!

                             

                            Spikeypup

                              • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                                revoc

                                Hi spikeypup,

                                 

                                Absolutely! Here is the information:

                                 

                                GPU: XFX RX 480 4GB

                                Monitor: ASUS VG245H

                                User manual for VG245H (supported operating modes is near the very last page): http://dlcdnet.asus.com/pub/ASUS/LCD%20Monitors/VG245/VG245_English.pdf?_ga=2.13790071.1785135889.1507470545-258508597.1507245254

                                Connection method: HDMI (this monitor does not support DVI or DisplayPort)

                                 

                                Specs with GPU Scaling ON:

                                display_specs_gpuscalingON.jpg

                                 

                                Specs with GPU Scaling OFF:

                                display_specs_gpuscalingOFF.jpg

                                 

                                Thanks

                                  • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                                    spikeypup

                                    I suspected this problem.  Which is why I asked for this with Scaling On/Off to confirm.  So thanks for doing that!

                                     

                                    If you note the Timings, you will see that without the scaling Windows is appropriately using the EDID information from your Display to achieve the 75hz, note the Pixel Clock is much higher, and the Horizontal Polarity is Negative, the Vertical and Horizontal Front Porch is reduced as well as the Horizontal timing width, which also all yields different and expected lowered Hor/Ver timing totals.

                                     

                                    With GPU scaling off, for some reason, Windows is deciding to use the standard LCD timings system, which for 1080P is always a pixel clock @ 148.5Mhz, and all the other associated settings you see in that snapshot.  For me, on my Asus display (MX279) using the standard timings, results in the blurriest most god awful image possible, well not really, but it's bad.  Of course, this is a standard timing that the monitor supports, as it should, but it definitely doesn't shine with it.  Actually since WDDM 2.0 and some pushes of Anniversary update but primarily Creators Update, I noticed many more complaints of "blurry text" or slight blur or washing of images in many of the Windows 10 forums that I also participate in.  At first I thought people were psycho, because how can a software update cause something like that unless it were severe GPU driver changes or the like, well the deeper I dug into it, the more it turned out to be an onion of a situation and it just got more stinky the more I peeled the layers.  Which works out for you lol because that's how come I learned so much about WDDM, monitor timings, display composition, and more boring things!

                                     

                                    Ok so there are a few ways to try to find out the culprit, as there can be a few.  One thing to rule out is a bad EDID on your monitor, since it works with scaling OFF, we know that the timing for 1920x1080 @ 75hz is there and is working fine, so it should be transmitting the information along DDC without a problem;  that's the Display Data Channel.  There is also the Extended Display Identification Data or EDID, which is a data structure used by displays and video/graphics output devices to communicate (DDC) and determine (EDID) the timings and capabilities of your display, so that the output device knows what and how to send the signal so the monitor can display the output correctly or at least within its operating specifications.  It also communicates things such as whether your display has speakers and how many, if it can decode Dolby or DTS, if it has deep color or supports 10-bit color, and much more.  When everything works correctly, you plug something in, it goes to the desired/configured resolution and refresh and you're done.  If the display has what's called a preferred resolution and timing, known as a "Detailed Resolution" then typically the output device will attempt to synchronize with the monitor based on this set of parameters, assuming the output device is also capable of the detailed resolution settings.  If not, then the output device typically attempts to synchronize on the next available set of parameters and so forth, this typically goes from highest resolution/refresh on down.  If detailed resolutions are absent or cannot be achieved by the output device, then standard resolutions are used, these use generalized timings or standard timings for LCD displays, in order to achieve the broadest compatibility between output and display, as well as to prevent situations where an image cannot be displayed regardless of setting.

                                     

                                    So history out of the way, with scaling ON your display is being set to Standard Timings, of which there is no standard timing typically built-in to an EDID for 1080P @ 75hz which is why you don't see the option, why the Detailed Resolution which includes the timing info that is obviously working (when scaling is set to OFF) is not being used, well that can be for a couple reasons.  The most probably reason is more than likely your composition and enumeration of displays contains an old subset of data for when scaling is ON.  Setting scaling to ON somewhat creates another display device as far as windows is concerned, which creates a new enumeration, and thus a new desktop composition.  Now if you never had scaling on before, then this should have been a new enumeration and the EDID data should have been passed through, but sometimes that doesn't happen.  Couple of questions:

                                     

                                    1. Is this monitor New?  If so did it replace the existing display? Did the existing/previous display use Scaling ON or OFF?

                                    2. If it replaced a Display did you connect this new one to the same physical HDMI port that the old one was using?

                                    3. Has this been the ONLY display you've ever used with this GPU?  Have you had other GPU's installed before on this current installation of Windows?

                                     

                                    I'll proceed with some general tips that might work without those answers, but please reply back anyway so I can compile the data especially if these tips don't help, but even if they work, please let me know the answers.

                                     

                                    Solutions to try in this order:

                                     

                                    1. Ensure that DDC is turned ON within the display settings.  On most displays you will find this in the menu settings, typically on Asus you will find it in the Menu-->System Setup--> OSD Settings --> DDC/CI--> Enable/Disable, according to your display's manual it is no different.  While typically if using EDID Overrides or a custom resolution I encourage most to have this set to OFF, but in your case let's try it with ON to ensure DDC communication with the GPU/Windows.  Once set to on turn the display power OFF and unplug the HDMI cable from the GPU side, not from the display.  Wait about 15 seconds or so, then plug the display back in to the same port, and power it on.  Check to see if the refresh rate table has updated in Display Settings.

                                     

                                    2. If that didn't work, as a quick fix attempt you can also try the same technique, but instead of plugging it into the same HDMI port, use a different port.  Using another port will cause the display to be enumerated by windows and will force a loading of the EDID information from the monitor which will include the timings etc.  If you've plugged it into the other port before, this may not work.  If it does work you can leave it this way and all should be well, however when you install new drivers, the problem may re-appear, although it shouldn't, it could.

                                     

                                    3. If it isn't a huge bother, you can also try to do a "Clean Install" of the drivers by selecting Custom Install --> Clean Install (the option is on the lower right of the window as a button) after starting setup.exe using the latest driver package in your C:\AMD directory.  In theory this will re-enumerate your monitor connections to the RX, however if the problem is currently in the enumerations to the Microsoft Basic Renderer, which I suspect this might be, then this solution may not work either.

                                     

                                    4. If you are at this step then the best solution in this case is to force re-enumeration of the display and display paths (GPU display paths/ports), which also forces an EDID download as well.  Because of the way WDDM works, which is too complex for me to dive into in this discussion, sometimes you end up with a Standard Display type of EDID being setup as one of the enumerations, such as when switching Scaling ON/OFF, sometimes the MS Basic Display Renderer slips in temporarily while the change is occurring, at this time often standard timings are assigned from this rapid enumeration, then when the GPU goes to grab the display path, it sees these timings and utilizes these instead of what is actually on the EDID.  How Windows stores the display data is not ideal in my opinion, as the display name and other data like S/N and manufacturer as well as enumeration data are not necessarily stored with the EDID and timing info.  So depending on how drivers call certain functions to the display subsystem and WDDM, sometimes they don't get back the ideal data, but they also don't know any better.   I will attach a tool that may help without the need to edit the registry directly to possibly correct this enumeration issue...

                                     

                                    5. As mentioned I have attached a tool known as CRU, Custom Resolution Utility.  It is very handy for setting what are known as EDID Overrides, these are monitor settings that you force windows to use regardless of what the connected device says.  CR's are used when you are having this kind of trouble or typically used when setting awkward resolutions that you might find yourself needing, or more commonly for Overclocking Displays.  I use it for those reasons, but also as a way to quickly delete unnecessary enumerations of displays and their associated EDID information.  This solution is not as complete as what I mentioned above at the end of #4, however it might work out for your situation and be quick and easy.  Simply follow the below instructions:

                                     

                                    A.  Set your GPU Scaling to OFF for this first run, we may run through it again with it set to ON, but let's try OFF first.

                                     

                                    B.  Open the CRU application by right clicking on it and selecting "run as administrator".  Ensure you do not have anything else running and make sure Radeon Settings is not open either.

                                     

                                    C.  Once open, you will have a dropdown in the top left, this shows all the monitors enumerated on your system, and will include displays that say "(active)" and ones that do not say "(active)".  Leave the ACTIVE monitors as they are, however for the displays that do not show "active", select the first one to not say "active" in the list, once selected, click on the "Delete" button as indicated in the image.  Repeat this for each monitor or entry that does NOT SHOW ACTIVE in the drop down box.  If you make a mistake, it's ok, just click Cancel and start over.

                                     

                                    D.  Once the only remaining displays in the list are the "active" ones, you can click OK to commit the changes.  Reboot your system.

                                     

                                    E.  Once rebooted, open CRU again as an Administrator, check the list of displays to see that the ones you deleted are no longer there.  They should not be there.  Click Cancel when done.

                                     

                                    F.  Open Radeon Settings, enable GPU Scaling.  Check display settings in Windows to see if the 75hz option has appeared.  If not, keep scaling set to ON for this next step.

                                     

                                    G.  Close all apps/windows, and open CRU again, as administrator, always as administrator.  Find the display in question in the drop down list, first checking the list to see if any other displays are appearing that are not Active, if so, delete the non-active ones.  Once that is done if necessary, find your Asus Display that is the one having trouble and is marked as "Active".  Delete it.  You will see that the button changes to "Keep" after you do that, because it knows it is active.  That's ok.  We're going to force enumeration of the display under the scaling path.  Once deleted, click on OK to commit the changes.  You will notice that nothing happened, at least nothing should have happened, that is fine.

                                     

                                    H. Now go back to Radeon Settings and turn Scaling OFF.  Verify that 75hz is showing still in the Display Settings or via "Specs" right there in crimson.  If set to 60hz double check windows Display Settings as it may have reverted down due to the delete, although it shouldn't have.

                                     

                                    I.  Now once verified, re-enable GPU Scaling setting it to ON.  Once it is active, now check windows Display Settings to see if the 75hz option is there or is set.  This should have worked.  Also, if anything goes weird, you can use the "reset-all.exe" application to reset the enumerations etc. and after a restart everything should normalize, but this should not be necessary based on what we are doing here.

                                     

                                    J.  If this did not succeed, then we will need to manually clear certain enumerations and desktop composition entries from the registry as there are conflicts/undesired setups saved in there causing this issue.  This particular solution is multi-part and requires you to make registry edits in the most extreme case, and in fact I will need to show you how to make edits as the "SYSTEM" user as the keys that need to be removed cannot even be viewed by any other user, not even Administrator.  The registry keys in question are safe to remove as they will just be recreated and re-enumerated during system restart.  This option is kind of last resort as it's not for the faint of heart or if you have no registry experience or gusto to do it. Let me know if we need to do that and if you are prepared to do that, if you are not comfortable you should have a friend that is comfortable with registry editing and is computer savvy assist you while using the guide that I will provide at that point, for now try the above.

                                     

                                    Good luck, I hope this works out for you!  Cheers!

                                     

                                    Spikeypup

                                    1 of 1 people found this helpful
                                      • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                                        revoc

                                        Incredibly informational and educational post!

                                         

                                        Here are the answers to your questions:

                                         

                                        1. Is this monitor New?  If so did it replace the existing display? Did the existing/previous display use Scaling ON or OFF?

                                        This monitor is new, as is the system (and GPU). I bought them at the same time. Thus, the only monitor this system has ever known is this one.

                                         

                                        2. If it replaced a Display did you connect this new one to the same physical HDMI port that the old one was using?

                                        It did not replace a display.

                                         

                                        3. Has this been the ONLY display you've ever used with this GPU?  Have you had other GPU's installed before on this current installation of Windows?

                                        This is the only display and GPU this installation of Windows has ever seen. I even did a completely clean install of Windows a couple of months ago (I like clean systems). OS is Windows 10 x64 Pro with all the latest updates.

                                         

                                        I don't have access to my system right now but I'll try out some of your suggestions when I have a chance. If this is a problem on Microsoft's side with WDDM let's hope they're aware of it and get it fixed, perhaps in one of their big bi-annual Windows updates!

                                          • Re: Can not set 75Hz on 75Hz monitor (rx480, latest driver)
                                            spikeypup

                                            Revoc,

                                             

                                            Thanks for getting back!  I'm very glad you found it informative and educational.  I honestly don't mind taking the time to be thorough because in my experience with forums like this, people would rather have the WHOLE story instead of the quick snippets, and I'd rather educate folks so they are more well prepared to handle things on their own if the problem comes along (you must whip it!).

                                             

                                            Based on your replies it would seem that we should be alright in the desktop composition and layout enumeration department, it's probably just a matter of the enumerated display for GPU Scaling.  If you follow the steps in order as I described, you should be alright and it should solve your problem.

                                             

                                            As for MS and WDDM, well I have been in touch with the team that handles WDDM/DDI + GDI and DXGI implementation, they are aware that the current enumeration and topological process is prone to these issues, at the same time through updates they have made pathways for developers to circumvent these issues... the problem is that this requires major rewrites of some very major driver components and fundamentals from the GPU vendors, so it's kind of a sticky situation.  I've seen AMD make great strides in adapting and implementing as many advanced features (along with the required of course) of WDDM as possible, but it doesn't help when MS makes changes to them constantly and even worse on fundamental levels.  This display issue is just one of a big handful of problems.

                                             

                                            At first I thought I was a bit of a quack when I stumbled upon the issue, but once I studied the WDDM structure/model, it all kind of clicked.  That's when I started to mess around deep in the registry with desktop compositions and display orders, enumerations, etc.  When I was able to accurately recreate the scenarios 100% of the time between the MS Basic Display Renderer Output path, and the discrete GPU Renderer Output path, basically forcing situations like yours, and then rectifying them through methods like I described above... then I knew I wasn't so crazy.

                                             

                                            The crazy thing is, this problem probably affects like 15-25% of users, without them even knowing.  I mean who checks their refresh rates, or even knows what that is?  And definitely people aren't looking at their pixel clocks and timings... let alone whether the display is even installed properly.  They just know that they plugged it in, and it is displaying something, if it doesn't seem right..."oh well it must be me" is probably the attitude.  When I first fixed my issue, I was amazed at how not only CLEAR my picture was, but how much smoother it was and that the GPU wasn't stuttering to get the frames out.  When I Overclocked my display my head almost exploded at the even further clarity and color depth, but the amazing smoothness from going 75hz+ (up to 90Hz on one of my displays rated for only 60hz of course...that I OC'd from 148.5Mhz up to 225Mhz!). 

                                             

                                            Now overclocking a display is a whole other matter, but people deserve to have their display render the way it is supposed to at the default settings, and with a default clock of 148.5Mhz on 1080P, there is no reason they shouldn't get that, after all that is the LCD standard for 1080P.  And most displays have their enhanced/preferred timings right there in the EDID, like right THERE!!! But for whatever reason, Windows loves it's defaulted 148.5Mhz; which I suppose for compatibility reasons it makes sense, it's almost always assured to work, but it doesn't mean it's the optimal setting... and besides if the EDID is telling you what to do, which it's supposed to, then why not follow it?  In my testing it's always a tossup whether or not Windows will properly enumerate a display upon connection, and you are worse off if it's already been enumerated and you move ports.

                                             

                                            Anyway, I'm ranting... but I can't help it, the problem concerns me, and every time I see someone who says "Can't change refresh rate", or "stuck at 59hz!" or something like that, I just sigh and think, how can this have been going on for over a year already...  And with that, I say... cha cha cha! 

                                             

                                            Spikeypup