PCI-E 3.0 (1Card vs 2Card)

[twpbknight]

Hello everyone so ive been thinking about going SLI in my rig but wanted to get some input first.

Im currently running a I7 3770k on a Gigabyte Z77x-UD5H which has 3 PCI-E 3.0 slots (16x,8x,4x). The question I have is

If I upgrade the GPU to sli the two cards drop to 8x mode on both slot 1 and 2. Will the performance be the same as a single card on the 16x slot? or how exactly would that work.

 

[SeekaX]

that wouldnt really make sense, right? it's just the bandwidth the cards can use, the performance with two or even three cards will increase a lot. the reason the bandwidth is getting smaller is that the mainboard can't handle the amount of data, that's also the reason why we are currently stuck with max 4 way sli.

 

[MrKambo]

Hello everyone so ive been thinking about going SLI in my rig but wanted to get some input first.

Im currently running a I7 3770k on a Gigabyte Z77x-UD5H which has 3 PCI-E 3.0 slots (16x,8x,4x). The question I have is

If I upgrade the GPU to sli the two cards drop to 8x mode on both slot 1 and 2. Will the performance be the same as a single card on the 16x slot? or how exactly would that work.

i think it works out to be 8x 3.0PCI-E = 16x 2.0PCI-E, dont quote me on it!

Anandtech did a review measuring bandwidth, it showed minimal losses dropping from 3 to 2, basically unless it was benchmark numbers, you wouldnt notice it in day to day use

 

[I Hunta x]

Yeah 3.0 8x = 2.0 16x B/W wise, its only noticeable in the 3-4 7970/680 massive res setups and even then its only a few frames from what ive seen.

 

[twpbknight]

That all makes since. Thx all for helping me on that

 

[alienware]

8x 8x when I tested it with a pair of 5770s in CFX was about 3% slower than when I ran it full 16x 16x in a very expensive high end Asus board (M3A32-MVP deluxe).

I'm running 16x 8x atm on a Z77 and I get a 19,000 GPU score in 3dm11 IIRC). About the highest I've seen was around 21k but that was a 2700k heavily overclocked rig (mine isn't).

You'll be fine. It's only when you drop the bandwidth to 4x that you run into issues as apparently SLI refuses to run on 4x lanes.