PCI Express 16x vs 8x

[HexiumVII]

I'm finishing up a computer with a cheapo Asus P5N-E SLI 650i that was $88, its a pretty damn good board for the price with SATA and nice o/cing. However i'm running a PCI Express RAID card and have to run in SLI mode to split the 16x physicals to 8x for the RAID to work. Will that be a significant hindrance in performance for the GTS? I'm thinking i could possible wait it out till the x38s come out or maybe with the P35s are out en mass. I will never run SLI video, though i maybe putting more raid cards

 

[aatf510]

I doubt it.

 

[KeithTalent]

There is some discussion on it here: http://forums.tweakguides.com/showthread.php?t=4040

Even though the cards in that discussion are older, from everything I have read the difference would be negligible.

I'll see if I can dig more stuff up for you.

Cheers,
KT

 

[tuteja1986]

A 8800GTX on PCIE 4x still wouldn't be disadvantage...

Take example of X1950XT AGP vs X1950XT PCIE... no real see able performance difference...

 

[Borealis7]

you english funny.

 

[Lord Banshee]

http://www.tomshardware.com/2007/03/27/pci_express_scaling_analysis/

 

[apoppin]

Originally posted by: tuteja1986
A 8800GTX on PCIE 4x still wouldn't be disadvantage...

Take example of X1950XT AGP vs X1950XT PCIE... no real see able performance difference...

i don't thinks so
-the x1900 series seriously lack bandwidth compared with the GTX

THG's conclusion

we found that only four PCI Express links are no longer adequate. Although there are differences between ATI/AMD and Nvidia, and between games and professional graphics, most applications deliver best performance at x16 PCI Express speeds. The two 3D games we used - Quake 4 and Call of Duty 2 - certainly cannot be called demanding these days, yet they benefit somewhat from faster link speeds. The professional benchmark SPECviewperf 9.03 was the real eye-opener, as it categorically disqualifies PCI Express link speeds below x16.

The benchmark results make pretty clear that chipsets and motherboards need to be capable of supporting all graphics cards at the full x16 PCI Express speed. If you run high performance graphics cards on inadequate interfaces such as PCI Express x8, you give away performance.

i could 'get away' with a 640MB GTS in my current MB for now ... and it would be a big improvement over my x1950p ... but a GTX wouldn't be ANY faster than the GTS ... and i would still be limited by my MB's equivalent of a 8x AGP slot for a 640MB GTS

 

[HexiumVII]

I did a bunch of testing with a test build with Rainbow Six Vegas, since its the current game i'm playing now and uses Unreal Engine 3. I found that i get maybe 2-3 frames difference at most. So i guess even 8x gives plenty of headroom. And they are trying to push PCIExpress 2.0 on us already.

 

[filibusterman]

Originally posted by: toattett
I doubt it.

agreed

 

[hans007]

at x4 it'd probably be a disadvantage. but x8 is probably enough.

 

[Fenixgoon]

Originally posted by: apoppin

Originally posted by: tuteja1986
A 8800GTX on PCIE 4x still wouldn't be disadvantage...

Take example of X1950XT AGP vs X1950XT PCIE... no real see able performance difference...

i don't thinks so
-the x1900 series seriously lack bandwidth compared with the GTX

THG's conclusion

we found that only four PCI Express links are no longer adequate. Although there are differences between ATI/AMD and Nvidia, and between games and professional graphics, most applications deliver best performance at x16 PCI Express speeds. The two 3D games we used - Quake 4 and Call of Duty 2 - certainly cannot be called demanding these days, yet they benefit somewhat from faster link speeds. The professional benchmark SPECviewperf 9.03 was the real eye-opener, as it categorically disqualifies PCI Express link speeds below x16.

The benchmark results make pretty clear that chipsets and motherboards need to be capable of supporting all graphics cards at the full x16 PCI Express speed. If you run high performance graphics cards on inadequate interfaces such as PCI Express x8, you give away performance.

i could 'get away' with a 640MB GTS in my current MB for now ... and it would be a big improvement over my x1950p ... but a GTX wouldn't be ANY faster than the GTS ... and i would still be limited by my MB's equivalent of a 8x AGP slot for a 640MB GTS

just remember that in THG's gaming benches, only the 8800GTS really suffered from x4 and x8 lanes, whereas the x1900 was fairly consistent regardless of the number of lanes provided.

so for an 8800, definitely get a mobo with pci-e x16 (and operates at x16)