PCI-E 2.0 x16 In Use @ x8

This is driving me crazy, I hope someone hear can help me..

I can not get my PCI-E X16 slot to run at x15 only x8.

I have updated bios, switched all bios settings to disabled for the usb/sata 3.0.

I have no other cards in my pce slots. I put the card in the second slot and it reads proper at x4.

I know the performace at x8 is almost on par with x16 but thats not what I bought.

PCI-E 2.0 x16 In Use @ x8 (Asus EAH5870 Video Adapter, ATI Cypress - High Definition Audio Controller)

this is from everest ultimate editon.

I have a gigabyte ga-p55a-ud3 .rev.1 bios f6. Asus 5870..

I5-750, 2x2Gb of kingston ram..

9 answers Last reply
More about tomshardware
  1. I wish I could help but I have no idea what's gong on either. It's either the mobo or card but I doubt it's the card because one card running at x8 after testing is pretty hard to miss. Got any other cards or mobos lying around for testing?
  2. Its pretty basic but do you have PCIe V1.1 compatibility checked in your bios?
    If so uncheck it...
  3. there is no pcie 1.1 in the bios...

    I dont have another board or card to test it with...

    I'm have RMA from gigabyte to send the board in.. Thursday I will put a new board in, I just got frustrated enough to order a

    EVGA FTW.... after rebates and bling came to about 160 bucks.

    Best case scenario is gigabyte replaces my board and I can sell it for 70 dollars or something...
  4. There might be an option in the BIOS for how fast the PCI Express bus is working? Not sure either. Disappointing to see that you have a $300 card and with limited performance
  5. Sorry we couldn't help, hey you have a backup in case this happens again!
  6. the card still does quite well.

    I did order the motherboard so it arrives thursday like said.

    dont worry about help 3 techs from gigabyte couldn't help either.

    I guess im the only one to have this come up I have not been able to find any

    other discussions on the topic.

    I used several different programs to make sure that I was only getting x8 width.

    So for those of you with this board or brand check to make sure its running at the

    correct speeds.

    The board is strong for overclocking, can run 4.0ghz all day stable.

    I well say this well be the last Gigabyte product I well ever purchase because the

    week it took to respond to my first technical service inquiry on their website.

    And the 3 more e-mails back and forth about things I had already stated in my

    original email to finally get a live person on the phone who was not very helpful..
  7. lauxenburg said:
    There might be an option in the BIOS for how fast the PCI Express bus is working? Not sure either. Disappointing to see that you have a $300 card and with limited performance


    limited performance, no, at pcie 2.0 x8 you get something like <4% performance loss, that is nothing

    @OP i would read through the motherboard manual very carefully if it says anything about the lanes being shared with something else
    my guess is another device is sharing at least one lane and dropping it to x8
  8. did read very carefully and it shares lanes with the usb 3.0 and sata 3.0.

    Nothing plugged into these and all bios settings including the turbo is disabled, so it should read at x16
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