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PCI-E speeds for R7770 crossfire

Discussion in 'AMD / ATI' started by Vaqz, Feb 3, 2013.

  1. Vaqz New Member

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    Hey, i have just gotten another XFX Radeon HD 7770 Black Edition and GPU-Z reports PCI-E Speed as x8 2.0 for my main card and x1 2.0 for my secondary card under load. What is also wierd is that after a reboot, both cards shows x8 and performs good, but after around 30-45 minutes of idling the speed of the secondary drops down to x1 and won't go up again. Also the Bus Width of the secondary card shows as 32 Bit at all times while the other is at 128 Bit, and bandwth shows 20.8 GB/s for nr. 2 and 80.0 GB/s for nr. 1.
    My specs are below.

    MB: ASUS M4A89GTD PRO/USB3
    CPU: AMD Phenom II X4 965 3.6GHz
    RAM: 12GB DDR3 1333 MHz
    GPU: XFX Radeon HD 7770 1GB Black Edition + XFX Radeon HD 7770 1GB Black Edition S
    PSU: 550W
    500GB and 1TB harddisks
    Windows 7 Ultimate 64-bit

    http://gpuz.techpowerup.com/13/02/03/s7.png

    Anyone have any ideas why this is happening? Help would be much appreciated! :)
    Last edited: Feb 3, 2013
  2. Jstn7477

    Jstn7477

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    Try the new card by itself in the first PCIe slot for a day and see if it works properly or not.
    Crunching for Team TPU More than 25k PPD
  3. d1nky

    d1nky

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    power saving features?
  4. Zubasa

    Zubasa

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    Likely this.
    Try running the 3D rendering test in GPU-Z and see if it goes back up.
  5. Jstn7477

    Jstn7477

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    The OP says he tested them under load, and you also can't turn off individual PCIe lanes, only change the PCIe version. Motherboards don't drop you from 8 PCIe lanes to being stuck on 1 lane an hour after being powered on.
    Crunching for Team TPU More than 25k PPD
  6. eidairaman1

    eidairaman1

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    http://www.anandtech.com/show/2952

    Check your Bios/UEFI settings (Update it if necessary) and Change those stupid Power Properties to max Power use for PCI E in Windows. Update your motherboard drivers then update your video drivers. make sure your case is clean including the components inside of dust, if the PSU is a few years old, get another. reseat your video cards.
  7. Vaqz New Member

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    I did check them using GPU-Z rendering test. My power settings are set to High Performance. I also have flashed to the newest BIOS and have the newest chipset and display drivers from AMD. I will try to use only the slow GPU tomorrow and check the results.
    Btw i currently use a 550W PSU, but i thought the cards didn't consume that much power. Is it enough?
  8. newtekie1

    newtekie1 Semi-Retired Folder

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    I'd definitely look at the PSU as a source of the problem. A really good quality 550w would probably handle it just fine, but a mediocre 550w could have problems.
    Crunching for Team TPU 50 Million points folded for TPU
  9. blibba

    blibba

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    This setup would pose no problems for a quality 350W PSU. What exact PSU do you have, OP?
  10. Vaqz New Member

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  11. newtekie1

    newtekie1 Semi-Retired Folder

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    Even when it was new that power supply was under-powered. It only had 30A(360w) on the 12v rail when it was new, and the caps being 3 years old probably means you are now closer to 20A(240w). I've seen 430w power supplies with stronger 12v rails than that PSU.

    A good PSU is a must for any system, but it is extra important for a dual-card setup. A new PSU is where I would start. You don't have to go all out and get a 850w unit, but a CX600 would server you well and they aren't all the expensive.
    Crunching for Team TPU 50 Million points folded for TPU
  12. Frick

    Frick Fishfaced Nincompoop

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    How is the power connected to the GPU's? Is there a way to tell the 12V lines from each other? Because that thing has three 12V rails, and if you're running the entire system on say one it I think you would have some problems..

    BTW, it seems it's the same as this one .

    EDIT: Did some digging, and it seems that it is a Delta unit.
    Last edited: Feb 3, 2013
    eidairaman1 says thanks.
  13. Vaqz New Member

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  14. gathor New Member

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    Hi
    So you use one line to supply power to both cards? I would try molex to 6pin adapter and see if running second card off separate line do some good. I got the same card (Super OC edition) running off my 400W PSU in shuttle without a problem (burn in test with furmark). I will check the PCI settings tomorrow (idle and under load). One reason for getting this card was performance/power consumption ratio as it is not that demanding.
  15. eidairaman1

    eidairaman1

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    adjust the high performance setting so the PCI E bus dont powerdown, i think its called link state.

    thats running off the same rail, normally 2 separate cards means 2 separate cables
  16. Vaqz New Member

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    Yeah now i have a Corsair 750W plugged in and connected. I've tried running both cards seperate and they get x8 speeds. But when they are in crossfire it still shows that the secondary is x1, even under GPU-Z stress test. And this PSU has seperate PCI-E cords.

    Anyone have any idea? :confused:

    I am now starting to think the faulty PCI-E slot is not working in crossfire.
    Last edited: Feb 4, 2013

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