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Memory OC Showdown: Frequency vs. Memory Timings

Staff
Staff
16 32 214K

The release of AGESA 1.0.0.6 to mobo makers has resulted in a wave of fresh BIOS updates, each one packed with tons of new options for tweaking and overclocking memory.1 With so many options at your disposal, some have understandably asked: “what are the optimal settings for games?” Never one to leave an overclocking question unanswered, our illustrious overclocker Sami Makinen took his ASUS Crosshair VI and AMD Ryzen™ 1700 CPU for a spin to find the fastest combination of settings in a few different tests.2

Before we dig into the data, here’s what we analyzed:

  • The impact of the new BankGroupSwap (BGS) BIOS option
  • Single-rank DIMMs vs. dual-rank DIMMs
  • Automatic sub-timings vs. manually-tweaked subtimings
  • Max frequency vs. lower frequency at tighter timings
  • Geardown Mode (GDM) on vs. off

Digging into geardown mode

Let’s start with the impact of Geardown Mode (GDM), as it’s easy to address.

GDM is enabled by default for memory speeds greater than DDR4-2667 per the DDR4 spec. GDM allows the RAM to use a clock that’s one half the true DRAM frequency for the purposes of latching (storing a value) on the memory’s command or address buses. This conservative latching can potentially allow for higher clockspeeds, broader compatibility, and better stability—good for the average user.

But what about overclockers?1 For overclockers, Geardown Mode will be noteworthy because it also tells the memory subsystem to "disregard" the command rate set in the BIOS. As 1T command rates can be beneficial (though tough to maintain) for performance, the chart below is really asking whether it’s useful to run GDM if the desired memory clockspeed can be achieved.  Spoiler alert: probably not.

pastedImage_1.png

Our data points indicate that Geardown Mode should be disabled for gaming if you can achieve your desired memory overclock with a 1T command rate. The opposite holds true if 1T CR proves too aggressive to reach your desired clockspeed--leaving Geardown Mode enabled may get you there. Finally, when it comes to GDM vs. 2T CR (not shown), specific memory throughput testing should be conducted as the balance of power will come down to your other memory timings.

BankGroupSwap

BankGroupSwap (BGS) is a new memory mapping option in AGESA 1.0.0.6 that alters how applications get assigned to physical locations within the memory modules; the goal of this knob is to optimize how memory requests are executed after taking DRAM architecture and your memory timings into account. The theory goes that toggling this setting can shift the balance of performance in favor of either games or synthetic apps.

Our data seems to bear this out: our games got a little faster with BGS off, while AIDA64 memory bandwidth was higher with BGS ON.

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Single rank vs. dual rank DIMMs

In the BankGroupSwap section, we alluded to “single rank” memory modules; that may have left some people scratching their head. That’s not surprising: memory ranks are largely unknown, not to mention cryptic. Starting from the top, PC enthusiasts know that a stick of memory is a circuit board with various memory chips attached. But have you ever thought about how a PC talks to those memory chips? That’s where ranks come in.

A “rank” is a group of memory chips that receive read and write commands as a group. Some memory sticks have all of their memory chips in one group, and those are single rank (SR) DIMMs. Other memory sticks split their memory chips into two groups, and those are called dual rank (DR) DIMMs.

DR modules can often be a smidge faster thanks to a capability called “rank interleaving,” wherein the second memory rank can still perform work while the first is being refreshed for use. However, DR modules are often harder for a system to drive to high frequency, which is why most high-performance memory kits use multiple 4GB or 8GB SR memory sticks. The extra frequency achievable by the SR memory modules is often enough to overcome the small performance benefit of DR DIMMs, too.

You can often tell single and dual rank memory apart by looking at the product code, which might say 1Rx4 or 1Rx8 for single rank, or 2Rx4 or 2Rx8 for dual rank. And though you should always verify with spec sheet, it’s a decent shortcut to assume an 8GB DDR4 DIMM is single rank, whereas a 16GB DIMM is almost certainly dual rank.

As we finally come to the data, our results lend credence that—all things being equal—DR memory configurations are a touch faster than SR configs for the purposes of PC gaming. But all things aren’t equal when it comes to overclocking memory, and we’ll explore that in the conclusion.

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Automatic timings vs. manual tuning

Every overclocker knows that memory runs on “timings,” which are various wait periods PC memory must make as it completes a full cycle of reading or writing data. Lowering the timing values (making them more aggressive) can yield better performance by shrinking the wait periods. However, timings that are too aggressive can easily lead to instability and memory corruption as the memory struggles to accurately read and write its own data.

Motherboards generally take on all the heavy lifting of setting the complicated list of memory timings through mechanisms like SPD and XMP. These timings are configured to balance the fussy triangle of performance, compatibility, and stability. But was there something being left on the table? Sami intervened to find out, and his results couldn’t be clearer: overclockers with the wherewithal to hand-tune their memory timings can extract notably better performance in the PC games we looked at. Some games might be less sensitive to memory timings, but these tasks seem to love it.

pastedImage_5.png
Full timings for DDR4-3200 “maxed”: tCL = 12, tRCDW/R = 12, tRP = 12, tRAS = 28, tRC = 54, tWR = 12, tWCL = 9, tRFC = 224, tRTP = 8, tRDRDSCL = 2, tWRWRSCL = 2, ProcODT = 60Ω.

The ancient debate: frequency or timings?

Last, but not least, Sami set out to find whether it was tighter timings or higher clockspeeds that mattered most on the AMD Ryzen™ processor. Sami pushed this combination of hardware up to DDR4-3520, DDR4-3466 with tighter timings, and DDR4-3200 with the tightest timings that could be achieved while maintaining stability with Memtest.

The verdict: tighter timings won. DDR4-3200 with aggressive timing adjustments outperformed the looser timings needed to hit DDR4-3520, while 3466 clearly split the difference with the right balance of timings and frequency.

pastedImage_10.png
DDR4-3200 “maxed” settings: tCL =12, tRCDW/R = 12, tRP = 12, tRAS = 28, tRC = 54, tWR = 12, tWCL = 9, tRFC = 224, tRTP = 8, tRDRDSCL = 2, tWRWRSCL = 2, ProcODT = 60Ω. DDR4-3466 “tuned” settings: tCL = 14, tRCDR/W = 14, tRP = 14, tRAS = 28, ProcODT = 60Ω, CR = 1T, GDM = Disabled, BGS = Disabled. DDR4-3520 “tuned” settings: tCL = 14, tRCDW/R = 14, tRP = 14, tRAS = 30, tRC = 56, tWR = 14, tWCL = 12, tRFC = 312, ProcODT = 53.3Ω.

Putting it all together

Now that we’ve picked through the data in isolation, we thought it would prove useful to take a mile-high view and draw some conclusions about what we found from our data set, and how that might impact gaming on the AMD AM4 platform.

pastedImage_11.png
DDR4-3200 “maxed” settings: tCL =12, tRCDW/R = 12, tRP = 12, tRAS = 28, tRC = 54, tWR = 12, tWCL = 9, tRFC = 224, tRTP = 8, tRDRDSCL = 2, tWRWRSCL = 2, ProcODT = 60Ω. DDR4-3466 “tuned” settings: tCL = 14, tRCDR/W = 14, tRP = 14, tRAS = 28, ProcODT = 60Ω, CR = 1T, GDM = Disabled, BGS = Disabled. DDR4-3520 “tuned” settings: tCL = 14, tRCDW/R = 14, tRP = 14, tRAS = 30, tRC = 56, tWR = 14, tWCL = 12, tRFC = 312, ProcODT = 53.3Ω.

  • Conclusion #1: Dual rank DIMMs (yellow) offered the best performance amongst “set and forget” (light blue, orange, yellow) memory configured automatically by XMP profiles.
  • Conclusion #1a: But the increased overclocking headroom of single rank modules was more than enough to overpower the benefits of rank interleaving, so manually-tuned single rank DDR4-3200 and 3466 won the day (dark blue and green).
  • Conclusion #2: BankGroupSwap should likely be disabled for users that want the best PC gaming performance. As always, test your specific use case.
  • Conclusion #3: Chasing the highest possible clockspeed required timings so relaxed that real world performance suffered versus lower frequencies with tighter timings. This is a fine balance, however, so testing on your platform is always helpful.
  • Conclusion #4: Geardown Mode should likely be disabled if your overclock is stable with a 1T command rate. As always, test your specific use case.

We hope these insights prove useful, and we’re looking forward to your feedback. Chat with us on Twitter @AMDRyzen or leave a comment.

32 Comments
Journeyman III
Journeyman III

Great post. thanks for doing this.. I still can't get my Corsair Vengeance LPX 3200mhz 5.39 kit (SK Hynix) to run at rated speed. I'm on an x370 msi pro carbon gaming motherboard. I've tried every BIOS version, including beta. My testing process usually goes like this:

1] try XMP profiles, that always fails

2] try manually setting memory clocks, that always fails

3] try manually setting recommended timings, that always fails

4] this is usually the step where I give up. I try raising memory voltage, SoC voltage, enabling/disabling geardown, changing from command rate 1T to 2T, try all the TryIt presets. Since it never helps I just fall back to my stable 2933/3200mhz and hope that maybe the next BIOS will make it easier.

Perhaps with the next BIOS I'll try some of the things you recommended.

Forerunner
Forerunner

Can you please share the Brand, model and specs of the RAM kit(s) used on the tests?

Adept I
Adept I

I am running G.SKILL Ripjaws V Series 32GB (2 x 16GB) 288-Pin DDR4 SDRAM DDR4 3200 (PC4 25600) and with the latest update for the Carbon I finally got it to 2800. What's also insane is that I put GeIL EVO POTENZA 16GB (2 x 8GB) 288-Pin DDR4 SDRAM DDR4 3000 (PC4 24000) in a Gigabyte AB350M-Gaming 3 and it hit max speed without the latest bios, I have since updated the bios.

Adept II
Adept II

Something similar with me. I'm having a 2x16 Corsair Vengeance 3000MHz CL15 kit, it couldn't go over 2133MHz untill I updated to AGESA1006 BIOS for my Fatal1ty board. Now it does 2666MHz CL16 without any issues, cannot go to 2933MHz. Still not sure should I try 2800MHz, but its still an improvement from 2133MHz, it really feels in a lot of instances.

Adept II
Adept II

I was able to get my trident z rbg ddr4 3200 32gb to run at 3200 with 4 dimms of 8gb sticks after the f4 bios update on the gigabyte aorus ga-ax3700-gaming k7 board

Journeyman III
Journeyman III

Yes, just as confused as I am

Journeyman III
Journeyman III

@amd, can you post like a profile we can flash to our bios?

Journeyman III
Journeyman III

How do I disable BankGroupSwap and GearDownMode?

Journeyman III
Journeyman III

After updating my Asus ROG STRIX B350-F GAMING to Bios 805 (AGESA 1.0.0.6) and selected the DOCP 2800 memory profile (ASUS XMP equivalent), my G.SKILL F4-2800C16D-16GRR are running @2800 with no problems whatsoever! 

Journeyman III
Journeyman III

**HOPE CAN HELPS!**

Hello, I'm using ASRock X370 Killer SLI, bios updated to latest one ( Version 3.00 ) , is says Update AGESA to 1.0.0.6a. But my GSkill FlareX 8GB x 2 3200Mhz it's cant run at fullspeed (3200Mhz). Always crash on BSOD with stopcode error?

Adept I
Adept I

With latest BIOS on my MSI Gaming Pro Carbon X370 and 1600X I can do 3200 on my Corsair Vengeance LPX 3200 8x2 (16) kit using XMP Profile.

The trick was buying the Samsung B-Die version (ver 4.XX printed on sticks). My previous identical kit was Hynix based (ver 5.xx printed on sticks) and would not properly run beyond 2667. I sold the Hynix based kit.

You really really want Samsung B-Die if you want to go beyond 2667 with the least effort.

Charles.

Journeyman III
Journeyman III

You can see this option on DDR RAM Timing Configuration on Motherboard BIOS.
*May variant on each motherboard.

Journeyman III
Journeyman III

if you are on the crosshair hero VI on 1403.

1. go to the advanced tab

2. go to AMD CBS

3. go to UMC Common options

4. go to DDR4 Common options

disable both bankswapgroups

Geardownmode is in

1.go to Extreme tweakers

2.then DRAM timing controls

Journeyman III
Journeyman III

It would be nice to overclock DR DIMMs and tune timings for comparing SR vs D

Journeyman III
Journeyman III

I currently have Hynix version of this kit ( 5.39 ) and I don't have any trouble to run my ram at 3200 MHz without XMP.

The XMP is not reliable, some kit won't work on profile 1 or 2. MB manufacturers don't have the time to tune their settings with new settings one very AGESA updates ...

Anyway AMD gave some tips for Overclocking Memory : ProcODT set at 60 ohms, tuning your sub-timings ( especially the tRC > tRAS+ tCL don't hesitate to increase it with Hynix chips ... ), CLDO_VDDP : 0.8v-0.9v for memory holes and increasing a little the NB/SoC Voltage ( currently I'm running at 0.965v )

The only problem I have with my MSI X370 Gaming Pro Carbon, is the memory latency ( Geardown and BankSwap OFF ), went back to 78ns ( It was at 68ns with the AGESA 1.0.0.4 ... )

Exemplar
Exemplar

I am also curious if there is any advantage to running 4 SR DIMMs versus only 2.

Miniboss
Miniboss

Thank you

Forerunner
Forerunner

Msi b350 gaming pro carbon.. I'm running Gskill 3200mhz, timings of 16-16-16-36, kit number is f4-3200c16d-16gvk...

Its running at 3200mhz and its hynix memory according to msi website.

I'm using bios , beta version 1.51

Has anyone seen any 3600 or 4000mhz memory running consistently on a ryzen system? specifically msi b350 gaming pro carbon?

Journeyman III
Journeyman III

I am running a Asus Crosshair VI Hero mobo, a 1700 and 32gb's of GSkill FlareX 3200mhzC14 ram. I have the cpu oc'd to 3933.6mhz, and the ram running at 3496mhz. This thing is blazing! I am getting 1760's on Cinebench cpu. I might be able to push things a bit higher as this was done pretty easily compared to how hard it was just to get it to a couple of points lower previous to reading this article. turning off those settings (BSG & GDM) really helped with stability. Also setting the Proc ODT to 40ohms was a big boost as well. I will try to push it to 55ohms tomorrow and try to hit 4000mhz on my 1700.

Journeyman III
Journeyman III

I would also love to know how Sami M got the ram oc'd to 3466mhz and kept the c14 timings???? I had to go up to c16.

Adept I
Adept I

This really is an amazing read, thanks so much for doing this.

Adept I
Adept I

Id also like to add my TwoCents I'm using the R7 1800X on The Crosshair VHero. Ram is the Team Group Vulcan I reviewed the Kit which can be found bellow, I have literally not had a single issue I was expecting loads tbh, but not one issue the Ram is rated @3000Mhz but since day one with the first Bios the board came with I've been able to Run it @3200Mhz simply by selecting the Standard DOCP setting in the Bios and said speed.

I'm on the Latest Bios now and still able to get 3200Mhz don't really want to push this Kit to much more really.

Team Group T-Force Vulcan 3000MHz Review/Perfomance when combined with the R7 1800X  

GARETH HUMPHRIES

I was expecting a lot of issues  but like I said not a single problem and performance scaled as it should with the faster frequency's.

I have now completed the Build added an AIO M.2 and captured all the extra footage I will update the Build log I posted for it with the new Pics and performance figures.

Build has truly ended up Beastly and stunning looks wise.

Exemplar
Exemplar

I have been able to run my 4X8GB kit at 3466 CL4.  To achieve that speed, I raised the DRAM voltage to 1.45, set ProcODT to 53.3 ohms and set the command rate to 2T.  The system will run stable with those settings, I have over 1000% IN memtest on it.

Journeyman III
Journeyman III

Great post. thanks for doing this.. I still can't get my Corsair Vengeance LPX 3200mhz 5.39 kit (SK Hynix) to run at rated speed. I'm on an x370 msi pro carbon gaming motherboard. I've tried every BIOS version, including beta. My testing process usually goes like this:

1] try XMP profiles, that always fails

2] try manually setting memory clocks, that always fails

3] try manually setting recommended timings, that always fails

4] this is usually the step where I give up. I try raising memory voltage, SoC voltage, enabling/disabling geardown, changing from command rate 1T to 2T, try all the TryIt presets. Since it never helps I just fall back to my stable 2933/3200mhz and hope that maybe the next BIOS will make it easier.

Perhaps with the next BIOS I'll try some of the things you recommended.

___

http://csgofreeskins.eu/

Exemplar
Exemplar

Unfortunately, I don't have any experience with Hynix memory.  The Corsair Dominator kit I have uses Samsung chips.

Adept I
Adept I

@memory-configration.jpg

I'm using same MB and memory module

(MSI X370 GAMING PRO CARBON and Corsair Vengeance LPX CMK16GX4M2B3200C16(SK Hynix ver.)

I tried to beyond DDR4-2933(of course,includes DDR4-3200)...

I forget How many times I configured memory timing...

Finally,I conclude this MB and memory module's margin is DDR4-2800.

Timing is 16-18-18-36-54,1T.

Of course,It's manually setting and GDM,GBS=OFF.

Let's Try it.

Adept I
Adept I

I have the GeIL DDR4 Super Luce 2400MHz  2x4gb kit, and Im running @ 2933 @1.35v with zero issues, GeIL just works, and loves the headroom that Ryzen provides.

Adept II
Adept II

Glad I found this article...good info!

I have recently come over to AMD and built a system around a 1920X

Got 3600 running and stable stable today!

3600.png

ramtest.png

But from looking at the data above I might try to fine tune a 3466 profile

Adept II
Adept II

OK so I took the timings from this article for the CAS 12...not easy to achieve but not too difficult either. 1.5v VDIMM 1.13vSOC

3200C121T.jpg

The same will get 3600 C15 stable

3600C151T.jpg

3600C151T3200percent.jpg

3600C151TRB1Hr.jpg

Exemplar
Exemplar

I've stayed at CL14 3200 MHz across my 4x8Gb DIMMs.  that was the best I could achieve and stay at 1.35V.  The Ryzen memory controller in summit ridge probably can't do much more with four DIMMs populated.

Journeyman III
Journeyman III

It can do much more than this. I'm running 4 SR B-die (Corsair Torque quad) @3466-14-15-15-15-1T (GDM off) and tight subtimings fully stable on my Crosshair VI with an R5 1600. This is at 1.425v.

Other quad kits need much less voltage for the same frequency and timings but the above is the only one I owned that also allows 1T with Gear Down disabled.

Journeyman III
Journeyman III

The true MVP is always in the comments. Thank you.