Windows 8 and 8.1 Forums

Radeon HD7950 x PCI-Ex 1.1 Slot - Significant Bottleneck ?

  1. #1

    Radeon HD7950 x PCI-Ex 1.1 Slot - Significant Bottleneck ?

    Some time ago I bought an ATi Radeon HD7950 3GB 384-Bit for my quite old system. I did have a huge performance gain moving from HD6870 to HD7950, but I'm not sure how far the board interface may be bottlenecking my card. My mobo has 2 PCI-Ex x16 v1.1 slots, what means that each slot operates @ 4GB/s.

    I found an article telling that the performance loss using one PCI-Ex 3.0 high-end single GPU card in a PCI-Ex x8 v2.0 (4GB/s) interface is very small for most games; so I guess it's the same for a PCI-Ex v1.1 x16.

    Moving from PCIe 2 x16 (8GB/sec) to PCIe 2 x8 (4GB/sec) incur a generally very small penalty on the 7970. However like most tests this is entirely dependent on the game itself. With games like Metro 2033 the difference is non-existent, while Battlefield 3 and Crysis only lose 2-3%, and DiRT3 suffers the most, losing 14% of its performance. DiRT3s minimum framerates look even worse, dropping by 19%. As DiRT3 is one of our higher performing games in the first place the real world difference is not going to be that great its still well above 60fps at all times but its clear that in the wrong situation only having 4GB/sec of PCIe bandwidth can bottleneck a 7970.
    Source: AnandTech - The Radeon HD 7970 Reprise: PCIe Bandwidth, Overclocking, & The State Of Anti-Aliasing

    What are your thoughts? Am I burning money?
    Last edited by vrosa; 22 Feb 2013 at 15:12.

      My System SpecsSystem Spec

  2. #2

    A PCI-E 1.1 X16 slot would support the same data rate as PCI-E 2.0 X8, or PCI-E 3 X4.

    Short answer: negligible effect, most of the time. Small effect, the rest of the time.

    Maybe the QX9770 is limiting things on its own, interfaces aside. In the US, it's be practical to upgrade to an I7-3770k, good midrange Z77 motherboard, and 8GB of DDR3, for about twice the cost of the HD 7950. If you wanted an I7-3930k, plus 16GB of RAM (4x4GB), it's be more like 3X the cost of the 7950.
      My System SpecsSystem Spec

  3. #3

    Good to hear that ! I will keep that rig as it is. My interest now is to invest my budget in a 6-core i7 system.
      My System SpecsSystem Spec

  4. #4

    Quote Originally Posted by vrosa View Post
    Good to hear that ! I will keep that rig as it is. My interest now is to invest my budget in a 6-core i7 system.
    Seems like a good idea. (See my system specs.)

    NVidia has had some issues with PCI-E 3 on X79 boards, but AMD supports it.
      My System SpecsSystem Spec

Radeon HD7950 x PCI-Ex 1.1 Slot - Significant Bottleneck ?

Similar Threads
Thread Forum
Drives plugged into USB/SD card slot won't detect/open
I went to plug in a USB external hard drive (via 3.0 slot) and the drive isn't showing up either automatically or on the "This PC" tab. If I go to the search function and type in "D:" I can find the drive and it's accessible. However, I can't figure out for the life of me why it's not just...
Drivers & Hardware
sd card slot
My sd card slot has worked fine on my 4 different sd cards since 8 came out, but suddenly all cards are read only (and work fine on other computer). So I believe it is a card reader hard/soft problem.... Any thoughts? Thanks
Drivers & Hardware
Which PCIeX16 slot should I use for a SATA3 card
My motherboard has 3 PCIeX16 and 4 PCIeX1 slots. I was planning to use an X1 slot but when the SATA3 card arrived I discovered (realised) it was X2 so I must use one of my X16 slots but which? Or doesn't it matter? More detail.... I currently use on-board graphics but may(?) get a graphics...
Graphic Cards
HD7950 won't work where 6950 does
So, I recently bought a Radeon HD7950, but when I put it into my PC, it caused all sorts of black screens and crashes etc. I used both a Radeon HD4950 and a HD6950 in exactly the same pc, and both worked without an issue. For my birthday I got a new 650W Power supply (replacing my old 500W, I...
Graphic Cards
DWM causing a significant performance drop in games.
Hi, after moving to Windows 8 I noticed a performance loss in many video games. After doing some testing I came to the conclusion that it is caused by the DWM(Desktop Window Manager) stealing CPU cycles from the games. In order to make completely sure DWM was the culprit I tested the same games...
Anything significant in new Win 8 update?
I hadn't opened my Win 8 laptop in a few weeks, and had over 20 or so updates to install and noticed one ws a fairly large update, non-security related update to Win 8. Anything significant in it? Thanks!
Windows Updates & Activation

Eight Forums Android App Eight Forums IOS App Follow us on Facebook