Windows 8 and 8.1 Forums


HD7950 won't work where 6950 does

  1. #11


    My house
    Posts : 148
    Windows 7 Home Premium x64


    Quote Originally Posted by my2cents View Post
    Quote Originally Posted by nenad285 View Post
    my2cents, my friend built a new PC using a Z77 chipset and his GPU is PCI-E 3.0 and has never had this issue. Besides the PSU being the probable cause, have you updated the drivers to the latest 13.10 beta for Windows 8?
    You answer is extremely generic! So, you think that because one configuration is known to work that all configurations should work as well? Any chance it is the same gpu and same mobo as the OP's configuration? I'll bet not. So, your answer is to just go out and buy a new PSU? My suggestion wil cost the OP nothing more than a bios change to test this issue. All the OP has to do is change the PCI-e 3.0 slot to run at Gen2 and see if that fixes his issue.
    Well I apologize for such a generic answer, I thought the option to change the lanes back a Gen was removed as the lanes change dynamically based on the PCI-E ver of your card.

      My System SpecsSystem Spec

  2. #12


    Well all that just goes to show that until some combination of HW is tried and tested and fat lady sings, there's no sure way to know.
      My System SpecsSystem Spec

  3. #13


    Posts : 2,191
    Windows 8.1


    Quote Originally Posted by nenad285 View Post
    Quote Originally Posted by my2cents View Post
    Quote Originally Posted by nenad285 View Post
    my2cents, my friend built a new PC using a Z77 chipset and his GPU is PCI-E 3.0 and has never had this issue. Besides the PSU being the probable cause, have you updated the drivers to the latest 13.10 beta for Windows 8?
    You answer is extremely generic! So, you think that because one configuration is known to work that all configurations should work as well? Any chance it is the same gpu and same mobo as the OP's configuration? I'll bet not. So, your answer is to just go out and buy a new PSU? My suggestion wil cost the OP nothing more than a bios change to test this issue. All the OP has to do is change the PCI-e 3.0 slot to run at Gen2 and see if that fixes his issue.
    Well I apologize for such a generic answer, I thought the option to change the lanes back a Gen was removed as the lanes change dynamically based on the PCI-E ver of your card.
    All I need you to do is explain "how" the Intel Z77 chipset is technically able to support the HD Radeon 7950 running at 3.0 speed? If you know, explain it, and if you don't know (technically), then just say "I don't know" because that's exactly my point so I'll say it again. "I don't know how the Intel Z77 chipset is able to technically support PCI-e 3.0." And this mobo has both.
      My System SpecsSystem Spec

  4. #14


    My house
    Posts : 148
    Windows 7 Home Premium x64


    If his Processor is a Ivy Bridge then it must not have a PCI-E 3.0 controller built in but instead a 2.0 which would explain why his GPU would run at 2.0 speeds. If he has a Sandy Bridge i5 that would also explain not running at 3.0 speeds as SB does not support PCI-E 3.0. As far as bandwidth goes, no gpu fully uses the PCI-E 3.0 bandwidth but still uses the bandwidth 2.0 has to offer. This is the info I know on PCI-E gens if it does not satisfy the answer you wanted then I'm sorry, I don't know and I hope the OP solves his issue and is able to finally use his 7950.
      My System SpecsSystem Spec

  5. #15


    Posts : 2,191
    Windows 8.1


    Quote Originally Posted by nenad285 View Post
    If his Processor is a Ivy Bridge then it must not have a PCI-E 3.0 controller built in but instead a 2.0 which would explain why his GPU would run at 2.0 speeds. If he has a Sandy Bridge i5 that would also explain not running at 3.0 speeds as SB does not support PCI-E 3.0. As far as bandwidth goes, no gpu fully uses the PCI-E 3.0 bandwidth but still uses the bandwidth 2.0 has to offer. This is the info I know on PCI-E gens if it does not satisfy the answer you wanted then I'm sorry, I don't know and I hope the OP solves his issue and is able to finally use his 7950.
    Hi nenad,

    Thanks for that response! With your explanation, then it looks like there is no way he could use that PCI-e 3.0 card. Let me break it down for you:

    If his Processor is a Ivy Bridge then it must not have a PCI-E 3.0 controller
    He does have a 3.0 controller.

    If he has a Sandy Bridge i5 that would also explain not running at 3.0 speeds as SB does not support PCI-E 3.0.
    Unknown at this point.

    As far as bandwidth goes, no gpu fully uses the PCI-E 3.0 bandwidth but still uses the bandwidth 2.0 has to offer.
    I already made that clear in a previous post.

    Actually, here's the way the mobo manufacturer's are implementing PCI-e 3.0 using the Z77 chipset:

    Click image for larger version

    Actually, you almost had it. The PCI-e 3.0 slot is required and it must be an Ivy Bridge processor. However, I still say the change to GEN2 speed might have worked and/or if he has a PCI-e 2.0 slot that might have worked as well. But I guess we'll never know because the OP has never responded since his opening statement and I can guarantee you that I will not be responding to this thread again becasue I have had it with the arguing over my recommendation to try a simple BIOS change and everyone else is recommending a costly PSU replacement. OK, I'm done.

    In any event, I am glad to hear someone else at least use the phrase "I don't know" in a response. Very refreshing.
      My System SpecsSystem Spec

  6. #16


    Posts : 2
    Windows 8 64bit


    OK, sorry for my lack of reply, I've just gotten back off of holiday. I will have a look at some of these issues when I have some time in the next few days, then report back with the results.
      My System SpecsSystem Spec

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HD7950 won't work where 6950 does
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