- Date:
- Monday , August 16, 2010
- Author:
- Brent Justice
- Editor:
- Kyle Bennett
- Share:

SLI & CFX PCIe Bandwidth Perf. - x16/x16 vs. x16/x8
Have you wanted to space your SLI or CFX video cards farther apart on your motherboard to allow for better airflow? Do you have a motherboard that will not support a x16/x16 PCIe configuration? We put x16/x16 and x16/x8 PCIe SLI and CFX configurations head to head and show you what sacrifice there is to be made.
ATI Radeon HD 5870 1GB CFX
Now we are going to use two stock AMD ATI Radeon HD 5870 1GB video cards. It will be interesting to see if RAM size affects PCIe bandwidth impact. We are going to test on a 30" Dell display with a native resolution of 2560x1600 as well as a triple display setup with a native resolution of 5760x1200. We are using the latest ATI Catalyst 10.7a BETA public driver.
We will run our testing in an apples-to-apples (A2A) scenario capturing real-world gaming frames per second. So these results can also be used for an A2A basis of comparison for performance across card configurations. So the results for AvP at 2560 are comparable for all SLI and CFX configurations, and AvP at 5760 are comparable for all SLI and CFX configurations, and Battlefield...etc. You will notice where some of the framerates are not playable settings as we usually do things, but considering the nature of this article we wanted every thing to be A2A.
2560x1600
Aliens vs. Predator
In Aliens vs. Predator at 2560x1600 with 4X AA we see the typical wild performance we’ve found so far in the other card combinations in this game since the gameplay is very dynamic. The result is that there was no difference in gameplay between x16/x16 and x16/x8 while playing this game.
Battlefield: Bad Company 2
In BC2 the average framerate is exactly the same, and minimum and maximum are very close. This game is not affected at all by reduction to x8 PCIe slot on the second video card.
Metro 2033
In Metro 2033, we see a slight advantage to x16/x16 here, but it wasn’t enough to notice any differences in-game. Also, in order to see this difference you have to play at a ridiculously high setting that is not playable at all.
ATI Eyefinity 5760x1200
Aliens vs. Predator
In Aliens vs. Predator at 5760x1200 with No AA we see a slight fps advantage to x16/x16, but it wasn’t enough to cause gameplay to change.
Battlefield: Bad Company 2
In BC2 there is still no real change in performance that changes the gameplay experience.
Metro 2033
In Metro 2033 there is once again no change in the gameplay experience.






