<Should those sockets be filled with Intel's quad-core Xeon chip, then you're talking bout 80 cores per chassis and 560 cores per standard 42U rack.>>

NOBODY can fill a 42U rack with ANY kind of blades without some serious refrigeration orthodontia ...

Arithmetic is great, but the laws of thermodynamics is greater. density doesn't mean SQUAT if ya can't cool it, and bro' NOBODY can cool that much CPU in that dense a space, even with ICE WATER forced through the rack.

Theory is swell, reality sucks .....

Using the E5310, with a decent airflow, it shouldn't bee too difficult to keep it cool. We don't even have industrial strength cooling in our server, room, and we have an entire 42U filled with Xserves running at 2.66, and those dual core variants of the XEON have a higher TDP than the 1.6GHz quad cores. Granted the cores are packed 40% tighter, but the difference in heat generated shouldn't be terribly great. On a side note, better to keep it cool than to let it go up in smoke.