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Graphics R9 290 not fully utilising PCIe Lanes

Discussion in 'Tech Support' started by abezors, 28 Jul 2014.

  1. abezors

    abezors Lurking since '08

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    Migrated build with:
    2500k
    Z77N-WIFI itx motherboard
    XFX R9 290

    Card is being limited by PCIe bus setting somehow -- it won't go above PCIE 2.0 2x speed meaning performance is severely hampered. On my previous motherboard it worked perfectly.

    On idle it runs at PCIe 2.0 @ 1x, rendering or games will push it to 2x speed (maximum 5.0 Gbps). On CCC hardware info says Graphics Bus Capability = PCIE 2.0 despite this slot being a PCIe 3.0 16x (which I understand is a limitation of Sandy CPUs).

    HWinfo also tells me max gaming power consumption is ~150w, I expected more but could be a red herring.

    Things I've tried:
    • Motherboard BIOS update to F4a (beta)
    • Disabling onboard graphics
    • setting BIOS PCIe generation to Gen3 or Gen2
    • reseating graphics a few times
    • cleaned PCIE slot and GPU pins with denatured alcohol
    • Flipped GPU Bios switch
    • added slight OC in Overdrive on CCC
    • upped PCIe freq from 100mhz to 101mhz
    • Swapped PCIe power connections in various configs
    • Swapped in a Radeon 5450 - still same problem

    I have moved from the exact same build as before, except now with the ITX motherboard. I have also added a full cover waterblock but cannot imagine this would cause any problems.

    Any ideas guys? I'm pretty desperate here...:wallbash::wallbash:
     
    Last edited: 28 Jul 2014
  2. jinq-sea

    jinq-sea 'write that down in your copy book' Super Moderator

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    An SB CPU won't do PCI-E 3.0, but that doesnt seem to be your problem here - it should still utilise all sixteen PCI-E lanes, just at PCI-E 2.x speed.

    Just for 100% checking, have you checked the CPU slot for any bent/out of position pins?
     
  3. abezors

    abezors Lurking since '08

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    Indeed, which made me think "hardware" - like bad PCIe slot or something. But having checked and cleaned all the pins in the 16x slot I'm fairly convinced it's not that.

    No, I haven't checked the CPU slot yet. Thanks for the suggestion, I will add this to my troubleshooting list to try later on (watercooling is a mission to detach everything)...

    Forgot to add I've tried latest AMD drivers plus the 14.17 beta, though both worked fine on the previous mobo.

    EDIT:
    Since this mobo supports UEFI, anyone know of better support with a UEFI graphics BIOS? Going to look into it, though probably won't flash yet.
     
    Last edited: 28 Jul 2014
  4. jinq-sea

    jinq-sea 'write that down in your copy book' Super Moderator

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    Aside from the CPU socket pins, I'm at a bit of a loss. Did you re-install your OS when you changed motherboards?
     
  5. abezors

    abezors Lurking since '08

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    Problem solved, in a fashion.

    Checked the pins as you suggested - all fine.

    Removed motherboard to give it a look under the magnifying glass and couldn't see anything wrong.. until I flipped it over and checked the backside. On the rear of the PCIe slot a couple of the SMD resistors have broken off and a couple more half broken but hanging on by a thread. Guess even trustworthy ebay sellers may be pulling a fast one :( I had never noticed the problem before as the last build was a HTPC/ hackintosh without a powerful gpu. So for anybody else trying to track down a strange fault, don't be too quick to dismiss physical damage just because you've looked after your hardware.
     
  6. jinq-sea

    jinq-sea 'write that down in your copy book' Super Moderator

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    I wonder if our very own Margo Baggins might be able to help on SMD duties here? Next time I speak to him, I'll ask if you like?
     
  7. jinq-sea

    jinq-sea 'write that down in your copy book' Super Moderator

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    I've dropped you a PM about a possible repair :thumb:
     

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