SmallBlaze :
My motherboard says it supports Dual Channel. Does that mean i can't have one stick of 8gb RAM, or do i have to have 2x4 RAM? Thanks
It's not mandatory that you need to install the memory in pairs. But in order to utilize the Dual channel memory architecture you need to have matching memory (speed, latency, voltage and probably size). So, if you are installing the 8GB module along with the existing memory then try to match the speeds and maybe that is enough to make 'em work in dual channel. Else single 8GB module is also not an issue.
Yes, there is a performance difference between different memory modes single, dual, triple and Quad. The diff b/w single and dual maybe around ~5-10% at max. I guess you have ordered the memory if that's not the case then try
Crucial.com or
Memorystock or whatever site you prefer. Good luck!!