The Cray X1 (also also known as the SV2 ) had a very innovative cooling method. A multichip module is mounted in a metal shell inside which four sprayheads delivere cooling liquid directly to the module face. Inside the sealed module the coolant to undergo a partial phase change extracting heat directly from the chips. The coolant is then returned through the larger hole and passed on to a heat exchanger. This direct spray cooling method had a number of advantages, firstly individual modules could be extracted and replaced without having to go through a full drain down of the entire coolant system, secondly the thermodynamics of the phase change could extract more heat than just a flow of coolant, finally the coolant was delivered directly under pressure to where it was needed most.
This video and talk about the Cray X1 CPU module with it’s interesting cooling arrangement over here at CPU Galaxy … X1 CPU teardown video here
This video introducing the Cray SV2 ( aka X1 ).
