quick test GTX 580 @ 8x pci-express

[z10m]

i'm thinking of buying another GTX 580 to run 2 in sli but my motherboard only supports 2x pci-e @ 8x/8x so i did some tests.

to run graphics card @ 8x pci-e i have isolated half of the pci-e slot from the card

and did some benching.

Metro 2033

pci-e @ 8x

stock clocks

Average Results
Average Framerate: 45.00
Max. Framerate: 113.75
Min. Framerate: 7.74

920/4700

Average Results
Average Framerate: 52.00
Max. Framerate: 206.14
Min. Framerate: 7.19

pci-e @ 16x

stock clocks

Average Results
Average Framerate: 46.00
Max. Framerate: 116.86
Min. Framerate: 8.17

920/4700

Average Results
Average Framerate: 54.00
Max. Framerate: 138.37
Min. Framerate: 6.62

Heaven Benchmark v2.1

pci-e @ 8x

stock clocks

FPS: 56.5
Scores: 1423
Min FPS: 6.0
Max FPS: 126.5

920/4700

FPS: 65.5
Scores: 1651
Min FPS: 29.8
Max FPS: 148.4

pci-e @ 16x

stock clocks

FPS: 59.4
Scores: 1496
Min FPS: 17.1
Max FPS: 130.6

920/4700

FPS: 69.4
Scores: 1749
Min FPS: 30.1
Max FPS: 148.7

is seems that GTX 580 is running at the edge of pci-e 8x bandwidth as when overclockig the difference between 8x and 16x is getting bigger
whats bizzare is that in heaven benchmark i'm getting less fps on sandy bridge platform than i had on my previous p45

enyone with GTX 590 dare to test it.?

 

[Postmodum]

So... your card is running faster on a x8 pcie slot than on a x16!?!?!? now that's weirdo

 

[z10m]

So... your card is running faster on a x8 pcie slot than on a x16!?!?!? now that's weirdo

are you sure.? look again lol

 

[Admiral Huddy]

What screen resolution you running these tests at? Lower resultions will require less bandwith so 8x may be fine.

 

[coltpython3]

So... your card is running faster on a x8 pcie slot than on a x16!?!?!? now that's weirdo

eh?

 

[iBSOD]

It's only about 3fps, I'd risk it. My motherboard does x8/x8(/x4) too and I am planning on SLI in the near future.

 

[z10m]

running it at 1920x1080 but also in 3D so i need 120+ fps to make games smooth.
dont care about antialiasing tho

 

[Postmodum]

Sorry ... misread it eheheh i was getting my eyes crossed from comparing the numbers

But, not huge difference ... what's good for users that have problems with x16 slot spacing and need to go x8 for sli, cf

 

[Admiral Huddy]

You are confusing the bandwidth with the effective speed. They are not the same thing.

Think of two cars doing 70mph on the M1. One car is on a 3 lane section the other on a 4 lane. The lanes are irrelevant as both cars are travelling at the same speeds. Where the car in the 4 lane has the advantage, is it can use the width as traffic increases.. but it still travel at 70mph. Conversely, the car in the 3 lane could slow down is it doesn't have the same width. so to speak..

The resolution does play an important part in the bandwidth.

 

[z10m]

so what you mean is that only high resolution is affected by pcie 8x and not overall speed.?