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

vrosa

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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. DiRT3’s 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 – it’s still well above 60fps at all times – but it’s 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?
 
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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 Computer

System One

  • OS
    Window 8 Pro
    Computer type
    PC/Desktop
    System Manufacturer/Model
    homebuilt
    CPU
    I7-3930k
    Motherboard
    Asus P9X79 Pro
    Memory
    16 GB Gskill DDR3-2133
    Graphics Card(s)
    eVGA GTX 680
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    Soundblaster Zx
    Monitor(s) Displays
    Asus PA246Q
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    1920X1200
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    Corsair Force GT 120GB
    WD Cavair Black 1.5TB
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    PC Power & cooling Silencer 750
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    Silverstone FT02B-W
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    Noctua NH-D14 w/ PWM fans
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    cheap Logitech USB wired
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    old 5 button Microsoft USB optical
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    6Mb cable
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 Computer

System One

  • OS
    Windows 10.0.10122
    Computer type
    PC/Desktop
    System Manufacturer/Model
    My Build - Vorttex Ultimate
    CPU
    Core i7 @ 4500 MHz
    Motherboard
    ASUS Z87-Plus
    Memory
    32GB DDR3 @ 1822 MHz (OC)
    Graphics Card(s)
    Radeon R9 280X 3GB @ 1180 / 6800 MHz
    Sound Card
    7.1 HDA
    Monitor(s) Displays
    LCD LG 22" + CRT LG 17"
    Screen Resolution
    1760 x 1320 / 1280 x 960
    Hard Drives
    1 x 240 GB SSD (System)
    3 x 500 GB HDD (Data/Media)
    1 x 2000 GB e-HDD (Backup)
    PSU
    ThermalTake 1000W PSU
    Case
    Corsair Carbide R300
    Cooling
    Corsair H60 (Push-Pull)
    Keyboard
    Microsoft Wireless Keyboard
    Mouse
    Microsoft Wireless Mouse
    Internet Speed
    60 Mbps (Down) 5 Mbps (Up)
    Browser
    IE, FF, Chrome
    Antivirus
    AVG Internet Security 2015
    Other Info
    Some wired stuff
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 Computer

System One

  • OS
    Window 8 Pro
    Computer type
    PC/Desktop
    System Manufacturer/Model
    homebuilt
    CPU
    I7-3930k
    Motherboard
    Asus P9X79 Pro
    Memory
    16 GB Gskill DDR3-2133
    Graphics Card(s)
    eVGA GTX 680
    Sound Card
    Soundblaster Zx
    Monitor(s) Displays
    Asus PA246Q
    Screen Resolution
    1920X1200
    Hard Drives
    Corsair Force GT 120GB
    WD Cavair Black 1.5TB
    PSU
    PC Power & cooling Silencer 750
    Case
    Silverstone FT02B-W
    Cooling
    Noctua NH-D14 w/ PWM fans
    Keyboard
    cheap Logitech USB wired
    Mouse
    old 5 button Microsoft USB optical
    Internet Speed
    6Mb cable
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