Graphic card dimension question

[Guest]

I have 2 8800 GTS in SLI and thought to replace them with 2 GTX 275 now length is not a problem but i was wondering if they are to wide to use conventional slots on an ATX board so would they fit or not. (this is assuming that there are no obstructions on the board to the card)

 

[Guest]

PS would a board with PCI-E x16 that are not 2.0 slow the performance of 275s or 295s noticably?