8 Replies Latest reply on Feb 21, 2017 8:35 AM by vengefulpanda

    R7 350 2gb ddr5 from Sapphire, limited 8x bandwidth instead of 16x and slow boot


      TLDR: Specifically, this newly installed card isn't achieving the full 16x bandwidth it is spec'd for even though it's in a PCIe 2.0 16x slot, and additionally, starting up the computer now takes an extra 30 seconds before post- the screens are just black for a while, no signal. Bootup and shutdown do function ok just slower, the card does more or less what it should, just in a kind of gimped way.


      Here the full information about what is going on, in a step by step fashion relating what happened and how I've tried to fix it thus far. Thanks in advance for any help!


      1. Issue appeared after upgrading system's graphic card from Radeon HD 6670 to Radeon R7 350. Motherboard is ASUS P5Q Pro, CPU Intel Quad Q6600 @2.4ghz. ALL EATX12v Power Cables (1x 8 Pin, 1x 24[?] Pin) are connected to MB and Ecosilent PSU is 750w. 8gb Gskill DDR2 Ram @800mhz. Display: Card is connected to 1x 1280x1024 NEC monitor VGA and 1x ASUS 1920x1080 monitor DVI. There is NO other card in any of the other PCIe 2.0 slots, and the other PCI 1.0 slots are empty as well


      2. With the previous card (HD 6670), I confirmed that the PCI-E Bus Interface information was "PCIe x16 2.0@ x16 2.0" i.e. the full available bus bandwidth WAS being utilized and IS still utilized when I returned the old card to the system to test. I used Display Driver Uninstaller to clean uninstall catalyst drivers before physically switching the cards out. I replaced HD 6670 card with r7 350 card in THE SAME PCIe Slot on Motherboard - that (blue PCI-e 2.0 x16 slot) closest to the CPU, and the primary, the one which my Motherboard manual said to use if only one graphic card is installed. The slot is a PCIe 2.0 x16 slot. It is the exact same slot which the older HD 6670 had been plugged into. I then installed the newest stable Radeon Crimson drivers.


      3. After the first time using the new card, I immediately noticed two changes to computer functionality (and slightly worse than expected gaming performance):

      A. 30 Seconds extra now elapse after starting PC before Motherboard Logo first appears, and shutdown time is increased.

      B. In AMD settings monitor (driver software), HWinfo64, and GPU-Z the following information about PCI-E Bus Interface is provided: "PCIe x16 3.0 @ x8 2.0" and "PCIe v3.0 x16 (8.0 GT/s) @ x8 (2.5 GT/s)". Basically, the card is being limited by something. In CPU-Z under "mainboard" I see the information "Graphic Interface: Link Width x8, Max Supported x16". The AMD Radeon Settings software simply says "Bus Type: PCI Express 3.0" and "Current Bus Settings: PCI Express 2.0 x8" but I CANNOT change the "x" value to 16 here OR in my motherboard's BIOS, as far as I know. I have spent a lot of time looking.


      4. Attempts to fix both the startup issue and to realize full PCI-e bandwidth of card thus far completely unsuccessful. Card PCI-e Bus Bandwidth remains at x8 (not x16) under load, i.e. playing BF3 at ultra settings or running 3DMark Firestrike, etc. Checked power saving settings, PC power plan is High Performance and power saving is not enabled in the BIOS afaik. Updated Motherboard Bios to newest version today, still no fix. Re-installed new AND old cards to test (ultimately leaving NEW r7 350 installed in the PC) and safely uninstalled/re-installed drivers multiple times, with no fix.


      Can anyone please help me figure out what to do about these two issues, the 1. long wait to boot and the 2. restricted PCIe bandwidth? Thank you!

        • Re: R7 350 2gb ddr5 from Sapphire, limited 8x bandwidth instead of 16x and slow boot

          I think your GPU cannot be successfully initialized by motherboard.It explains both issues.

          1.Update BIOS

          2.Delete C:\AMD folder

          3.Uninstall all AMD software and clean your system in safe mode by DDU programand install 16.11.5 or 17.2.1 driver

          2.You can reinstall your GPU in PCIe slot more tightly and clean this slot from dust before GPU installation.

          3.Also you can try your GPU on another PC

          4.But 8X2.0 is already overkill for your GPU:

          PCIe speed.png

          1 of 2 people found this helpful
            • Re: R7 350 2gb ddr5 from Sapphire, limited 8x bandwidth instead of 16x and slow boot

              Thanks a lot for your response! I'll go ahead and try those steps you mentioned, namely the comprehensive re-install of the card with deletion of the AMD folder. I had wondered if the motherboard was somehow reading the card as being in crossfire mode but both the AMD settings utility and GPU-Z are telling me that crossfire is not enabled.


              Some of your suggestions I have already attempted, specifically updating the BIOS to the newest version (did nothing) and blowing significant amounts of air into the PCIe slot as well as cleaning the card of dust (there wasn't any really because the card is fresh out of the packaging, anyway this also didn't help). I did re-seat the card multiple times and I am afraid to push down on the motherboard any harder than I already have. The card seems to be as tightly in the slot as it is possible to accomplish.


              I had thought that my uninstall/install of the previous card's drivers was as clean as it gets but in fact all that I did was boot into safe mode and uninstall the drivers using the same utility you suggested, DDU, and then I used AMD's hardware monitor to find and install the correct drivers for the new card. I have done this multiple times now.


              I have indeed heard that this low end card does not necessarily need to be running at x16 to perform as well as it can. Still, I hope to find out the reason for the limited bandwidth, as this and the boot issue never appeared with the old card. I'm just confused about why the lane width is maxed with the other card but not this one. Do you really think it is just a motherboard/graphics card compatibility issue? the r7 350 came out in 2015 but is meant to be a redux, or repackaging, of the hd7750/hd7770 cards which came out in early 2012, less than one year after the HD 6670, if I am not mistaken, and it should be fully backwards compatible with the primary PCIe 2.0 16x slot on my P5Q motherboard. Thanks again for your help!