2011/8/5 Pedro Paulo de Magalhães Oliveira Junior ppj@netfilter.com.br:
In my experience you'll have the benefit of using two cards simultaneously. That means you can run two recon-all with gpu acceleration simultaneously. The SLI is more important for graphics (cad, gaming) than for CUDA. So, I'd go for 2 GTX580
CUDA doesn't use SLI at all - you don't want it. So long as each card has enough RAM to handle one recon job, having more cards and using the environment variable to select the GPU is certainly the way to go. I don't think that Freesurfer is particularly heavy on the PCIe bus, so you should even be able to get one of the dual GPU cards and get good performance. However, Nehalem does help the data reorganisation required for the GPU.
Richard