Quote from radist:
If you're only using one monitor, my understanding is that the graphics is already integrated into the Sandy Bridge i7 2600K -- so no card is needed at all.
Depending on how many monitors you want to drive. I'm told (and unconfirmed) that to use another graphics card that the integrated one will have to be turned off.
I'm also told that the main reason the 2600K benchmarks so good is due to the integrated graphics, and that the benchmark drops significantly when an auxiliary graphics card is used. Also the 1155 socket boards have limited PCI-E lanes (32? 28?), hence the limits on how many PCI-E boards will actually run at 16x. The 2600K/1155 is not an Enthusiast platform.
IMPORTANT
Sandybridge 2600K may not be what some of us are looking for.
http://www.elitetrader.com/vb/showthread.php?s=&postid=3063466#post3063466