hi guys i have a gigabyte GA-EX58-UD5 and currently have an i7 920 and a gtx 580 in it right now and looking to upgrade it, my question is whats the smartest cpu to buy for it and would it be better to put another gtx 580 in it (my friend has a spare) or do i just upgrade to something like a gtx 700 to 900 series, also if i put a higher end card in straight away will it bottleneck with my i7 920, thanks if anyone can reply!