this is one of the articles I read and it talks about an i7 765 with 3 GTX 280's and the bottleneck seems to go back and forth.. but I cannot get a 765 so this article while helpful for people with 2grand to spend on a computer is great really doesnt help me understand bottlenecks for the 920.
btw this is a great article.
note: I have a suspicion that the 920 has similiar bottlenecks but nothing that I can find has been proven that it does.
Yes thats a good article.. another thing to note there is that 2 260's are as fast as a 295, the bottleneck there is the single x16 slot as opposed to two x16 slots.
There was also an article done by tomshardware about GTX275 sli vs GTX 295 in which they blew away (for the most part) the 295 and they hypothesized that it was a channel limitation and not gpu limitation. Which would make you wonder how much faster are we going to be able to go without a major architecture change from usb express to ?
for the money right now the 260's seem the way to go.