nah, going for 2.0 cards wouldn't give you bottleneck since 2.0 pcie slot are backward compatible with any 2.0 or 1.0 cards...
But wouldn't I get less bus speeds by using a 2.0 card in a 1.0 system?
16 lane slot:
v1.x: 4 GB/s
v2.x: 8 GB/s
My 680i board is running a pair of 8800GT's just fine and according to the specs they're PCIe 2.0.
I understand the compatibility but, for my situation, what is the point of buying a 2.0 card if their bus speeds will be limited? Sure I could buy 2.0 cards and run them alright I suppose, but why not just wait until 3.0 cards come out? Or even if I were to make a system right now, buy 2.0 cards later down the road when they're cheaper?