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View Full Version : Dumb x8 vs x16 sli question


Bladestorm
10-27-08, 03:20 PM
Two 8800GTX's in SLI running in PCIe x8 slots is still going to be faster than a single 8800GTX at x16, correct?

Bman212121
10-27-08, 04:14 PM
Yup, 8800GTX cards won't saturate an 8x PCI-E bus, so there won't be any issues there.

Bladestorm
10-27-08, 04:19 PM
Thanks.

I saw some benchmark somewhere that compared two cards in x8/x8 vs the same cards in x16/x16, and the only real difference was at high resolutions in Crysis. Then again they were using ATI cards. I just don't want the idea stuck in the back of my mind that I "could" be getting better performance.

Bman212121
10-27-08, 08:08 PM
Nope you won't see a difference. I've seen tests done in the past with 8800GTX cards which showed no difference. I used to have a DFI board with only 8x lanes, so I was looking before to see if it would help or not.

john19055
10-29-08, 02:09 AM
I ran my two 8800GTS 640mb in SLI with a Asus 650i SLI that are just 8x each,so I bought a EVGA 680i SLI with support for both cards to be able to run at 16x each.I think I gained 90 extra in 3Dmark 06 ,which is in the area of tollerance.But in games I could not tell no difference.

rage10
10-29-08, 06:36 PM
do the gtx 200 line saturate the bus?

Bman212121
11-02-08, 08:41 AM
That's the 2nd time I've seen that question come up, but I honestly don't have an answer. I can say you will not need a PCI-E 2.0 slot to get the full use out of a GTX 280, however I'm not sure about an 8x slot.

It would seem kind of hard to find a board that has only 8x slots if you're planning on using SLI. I don't see someone buying a $50 board to put $800 in graphics cards in it. I also don't think too many people are going to be using Socket 939 or pentium D setups with that much graphics power.

rage10
11-04-08, 09:45 PM
I was refering to an 8x pci-e 2.0 slot. it has the same bandwith as a x16 pci-e 1.0 of 1.1 slot right?

Bman212121
11-05-08, 01:11 AM
I was refering to an 8x pci-e 2.0 slot. it has the same bandwith as a x16 pci-e 1.0 of 1.1 slot right?

Yes it does.

http://www.tomshardware.com/reviews/pci-express-2-0,1915-2.html

From that article PCI-E 1.1 runs at 2.5ghz, PCI-E 2.0 runs at 5.0ghz. This doubles the bandwidth for PCI-E 2.0, so it's 8GBps for both slots.