Originally Posted by Vanzagar
Just to clarify, does SLI tax a system more than a single card solution of similar horse power... for example would my system run near the same with 2x HD6970 vs. HD6990 or would my system perform better with the single card solution or the HD6990?
If so why is that?
It's not a question of "taxing" the system as much as "introducing a bottleneck".
So if you have an HD 6990 or 2x 6970's or whatever super-powerful-graphics-setup, the graphics cards will have the capability of pumping out more FPS. However, the CPU is also able to pump out only a certain number of FPS (that's why review sites measusre CPU performance in low quality mode). If the max amount of FPS a CPU can pump out is LESS than what your GPUs are capable of at a given setting point, then you are limited to whatever your CPU can pump out. Reverse argument applies if the CPU can pump out more frames than the GPU (you're limited to whatever your GPU can pump out).