Hitachi make dual Opteron water cooling system
 

Didn't know Hitachi was into system cooling, this all-in-one water cooling solution seems ideal for OEM:

"The new self-contained thermal solution will be used with two AMD Opteron 2220 (2.8GHz) processors in the HP xw9400/CT Workstation. Low noise and heat management were primary reasons HP chose watercooling, and subsequently the system produces at most 26dB under high load.

http://www.frostytech.com/permalink.cfm?NewsID=56112