OpenGL programming with SLI


I’m writing applications on Microsoft Visual Studio 2005 using the OpenGL .

My computer has two graphic cards with SLI configuration (nVidia 9800 GT). Using different benchmark programs I checked that SLI is working properly.

How can I utilize the SLI configuration in my code? Do I have to include or link any additional libraries to my project? Do I have to use OpenGL extensions?


OS: Windows 7, 64 bits
Driver: 191.07
CPU: i7 920

SLI is completely transparent to your application. The driver presents the two cards as one device to the OS, and does the ‘magic’ for you.

If you want to program the cards individually, you have to disable SLI and address them as two cards, e.g., using Equalizer (


The problem is that I cannot detect any difference between working with one card or with two cards. I expected to get an increase in the FPS rate.


Did you read the nvidia perf guide ?
There is a section about how to take best advantage of SLI.

Short version: If you’re not fill-limited, SLI won’t do a darn thing for you. In fact, I’ve read it may actually even slow you down.

Much more interesting possibilities exist using two cards without SLI.

P.S. AFAIK this applies to GX2-style cards such as the GTX 295, not just multi-card SLI.