![[H]ardOCP](/images/blank.gif){kind=small}
- Date:
- Monday , August 16, 2010
- Author:
- Brent Justice
- Editor:
- Kyle Bennett
- Google +1
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.
NVIDIA GeForce GTX 480 SLI
We are going to start with NVIDIA’s GeForce GTX 480 SLI. We are using two reference video cards with standard clock speeds and SLI enabled. 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 NVIDIA ForceWare 258.96 WHQL 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 what is the reverse of what we would think is correct. As you will see, we don’t see this same reversal consistently and ultimately will help prove how using one x8 slot really doesn’t affect the gameplay experience at all. The performance is extremely close here, and just depending on your style of gameplay will affect performance more than anything.
Battlefield: Bad Company 2
In BC2 we see this again, where x16/x8 is ever so slightly faster, but it is so close that these variances are all within the margin for error. In essence, gameplay performance is the same.
Metro 2033
In Metro 2033 we see x16/x16 edge out the x16/x8 just slightly, but it is so slight that it does not represent any difference in the gameplay experience.
NV Surround 5760x1200
Aliens vs. Predator
In Aliens vs. Predator at 5760x1200 with No AA we see nearly identical performance, which is much closer than it was at 2560x1600 with 4X AA.
Battlefield: Bad Company 2
In BC2 we see close performance, but it is slightly more in favor of x16/x16 than any other test so far, but the difference isn’t that big and not noticeable in-game.
Metro 2033
In Metro 2033 performance matches perfectly, there is nothing to see here.