SLI & CrossFire

[Apollo1020]

I would like to know everything (or at least something) about NVIDIA's SLI and ATI's CrossFire. I know, that SLI made by SLI bridge... but does it comes with graphics card? I know nothing about CrossFire... does it connects thrue a bridge or somehow else?

If someone, who knows what it's all about - please, tell me. Thank you.

 

[Apollo1020]

Still waiting on someone's reply... but, by the way - I need information on how much in percents (%) performance is raised with NVIDIA's SLI and ATI's CrossFire (if at least 2 GPUs)... this is very important!