Quote:
Originally posted by Sirpent
myv65,
By efficiency i ment the (lower) cpu temperature under given heat produced by cpu and given ambient temperature. But my question was rather about idealized equations (proportionality of heat transfer to delta-T's) than about real life situations.
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Yup, the can's open! Lowest CPU temperature for a given ambient will vary from system to system and chip to chip. At one extreme, you could have flow so low that convection in the block was awful. In order to carry "X" watts, the water would need to go through a large delta-T and due to the low flow/convection coefficient, the chip would need to be a lot hotter than even the warmed fluid. At the other extreme, you could conceivably pump far more energy into the water just to pump the volume than what energy the chip would add. Delta-T in the fluid would be extremely low, but at some point you may have rising temperatures simply because of the energy needed to pump the water around.
Call it cheating on my part, but there is no single answer that covers every system. There is, however, a general rule that most systems will provide a lower cpu temperature as flow rates increases.
More practically speaking, performance from one system to another will depend far more on how you set things up than anything else. Put your radiator in a spot where it has trouble getting air, bad news. Get a block that refuses to clamp down properly, also bad news. Do everything right and you'll be hard pressed to find more than a few degrees C between decent systesm.
My only real beef with designers of this stuff is that they don't do things as efficiently as possible. Given water's specific heat, you don't need much flow to get the job done. What you *do* need is high convection, aka high velocity in the block. With the right porting, you could cool the CPU with <20 gph easily. Why this matters is that it would allow smaller pumps and smaller radiators. I'll admit that the delta-T in the fluid would be higher than a system running ~75 gph, but so what? The cost, both purchased and operating, would be lower. I guess that's why some things ya gotta do yourself. It's also why I won't be running a pre-built system any time soon.