PCI-EXPRESS 2.0 HELP NEEDED

[rc51kodiak]

What are the performance gains from a board that will run two video cards simultanously at 16x versus one slot running 16x and the other at 8x in dual card setup?

 

[FallenSniper]

There is no real loss from running in 8x instead of running in 16x mode. The bandwidth on the slot doesn't really create a bottleneck in most cases. I would estimate something like the second card running in 8x instead of 16x could result in a 0% - 3% performance loss. Nothing to write home about.

 

[Uberragen21]

What are the performance gains from a board that will run two video cards simultanously at 16x versus one slot running 16x and the other at 8x in dual card setup?

Well, the biggest problem with purchasing a board that supports one card at x16 and one at x8, means if you run 2 cards in SLI, both cards will run at the slower speed (x8). Like most all things in a computer that are linked (memory, video cards in SLI/crossfire, copying files from 1 HDD to another), they will ALWAYS run at the speed of the slower one. Now, if you're not really looking for the best performance, and don't have the best video card, or don't game, then it's not a big deal. But then why would you be looking to run 2 cards in SLI. Don't short change yourself, get a board that supports x16 in both PCIe slots.

When I built my system, I made darn sure I spent the extra $$ to buy a board that ran both PCIe at x16 speeds.

 

[4745454b]

I would agree with Fallensniper. In real world applications, the difference between 8x/8x and 16x/16x is almost nothing. More so if they are PCIe2.

http://www.tomshardware.com/reviews/crossfire-pci-express,2095-5.html

If you look at this review, they test CF with several different boards. They range from 4x/4x to 16x/16x. You might see the occasional odd result, but the x48 (16x/16x) and the P45 (8x/8x, both are PCIe2) are mostly the same. Honestly the x48 isn't worth the extra money.