PCIExpress X8 & X16 & 2X8, scaling on Heaven 2.0 DX10 With all ATI Radeon HD 4870 X2

[theoldtimer]

I always wondered if my FPS in games or the graphics sores in benchmark tests were affected when I installed my GFX card in an X8 PCI-e slot. When I ran a benchmark and the graphics score appeared low I would usually assume it was because I had the graphics card install in the X8 slot. I thought it was about time I tested the X16 and X8 slots to prove or disprove the X8 slot being the problem.

The MSI 890GXM-G65 motherboard’s PCI-e spec. is slot #1= X16 (single card), PCI-e #2=X8 (single or as the second card installed) or when two GFX cards are installed PCI-e #1=X8 and PCI-e #2= X8.

Test system
MSI 890GXM-G65 MB -OS=Windows Vista 32-bit.
965-C3 @4.55GHz
4GB total memory 2x2GB Corsair 2000 CL8, @1640MHz 6-6-6-24 during testing
Test boot drive=80GB-IDE
GFX card(s)=1 or 2x4870x2’s @778/980 air cooled
CPU cooling =chilled water (windshield washer fluid) fluid temp=-10/-15C
PCIe bus speed @ default (100) in the bios

I ran three tests of each PCI-e slot #1 x16 and #2 x8 using 1x4870x2 GFX card. I averaged the results of each three run set to find the test results for each PCI-e slot. The screen shots are of the last test or third test of each three test set. I also posted one screen shot (bottom of post)of a test ran in quadfire (2x4870x2’s).

The CPU @4551MHz 1x4870x2 @778/980MHz Vista 32-bit

PCI-e slot #1 average of three tests
FPS=103.6
Score=2610
Min FPS=52.6
Max FPS=209.4

PCI-e slot #2 average of three tests
FPS=102.7
Score=2586
Min FPS=51.4
Max FPS=207.9


PCI-e test slot #1 x16 third test Screen Shot with Catalyst Control Center




PCI-e test slot #2 x8 third test SS with CCC



PCI-e test both slot #1 and #2 both @ x8 quadfire 2x4870x2’s

[mcmeat51]

try 4x, Id like to see the effect of that?

cheers

M

[theoldtimer]

I'll check and see if I have a MB with a PCI-e slot that is locked @X4 or can be bios set to X4. If I do I'll be happy to run a comparision test for you.

[Leeghoofd]

Thx for the tests Oldtimer

Finally someone that proves that there's not much going when you only got 8X at your disposal. (had a big discussion with some fellow reviewers on this matter) The performance loss is really negligable with most cards... as what I told them guys too (they claimed performance was drastically influenced ). I've done similar tests on X58 ( for benching purposes only ) and results were similar to yours...

[theoldtimer]

It is interesting and the results were a little eye opening for me. Which GFX cards were you testing?

[Hocevar]

What about PCI-E 1.x 8X ? As far as I know PCI-E 2.0 doubles the bandwith so even at 8x it doesn't affect the performance.

[Leeghoofd]

It is interesting and the results were a little eye opening for me. Which GFX cards were you testing?

2 x 8800GTS512 and 2/3 x GTX 285...