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Cathar · 10-23-2002, 05:45 AM

What you're basically asking is how to design a water-block scientifically.

It goes (roughly) like this:

1) Define target pump pressure
2) Derive optimal orifice size as a balance of pump pressure, water velocity, and volumetic flow rate.
3) Define target die size. Heat load is basically unimportant. Assume 100W (real watts - not fake Radiate watts) as a peak
4) Determine what material you're going to make the waterblock out of.
5) Derive structural integrity constraints to cope with up to 50kg of pressure over a 1cm^2 area given the material you've chosen.
6) Machine the material in a way that maximises the water surface area within 2mm of each side of the CPU die (ie. for a 10x10mm die, target a 14x14mm area to maximise surface area over)
7) Using 2) above, derive a method to maximise the water turbulence over the die area specifically - this will be greatly affected by the design you've chosen in 6)
8) After 7), derive the maximum height required of the water-block material and the base-plate thickness. These two are linked more strongly that one would first imagine. Determine this for your 100W heat load. Target the fin/channel/block height at the 98% dissipation mark. Meaning that 98% of the heat is being dissipated below that height. Basically this defines an upper limit to the useful height of the block. As a hint, for copper/100W/water, if you're focussing on anything above 8mm, you're going in the wrong direction, unless you have pathetically low flow rates/pump pressure.

After you've defined 8), you'll then learn that this impacts on 7), and almost always on 2), so you'll need to reiterate the process to refine it, while will undoubtedly bring 6) back into the mix as well, while keeping a very close eye on 5).

Keep refining and reiterating those points and you'll asymptotically approach the limitations of the waterblock's efficiency with the design architecture and machining method you've chosen.

I've been doing this reiteration process and managed to squeeze even more performance out of my design, but I'm also rapidly approaching the limitations of what can be done with the machining equipment I have access to.

10-23-2002, 05:45 AM	#128
Cathar Thermophile Join Date: Sep 2002 Location: Melbourne, Australia Posts: 2,538	What you're basically asking is how to design a water-block scientifically. It goes (roughly) like this: 1) Define target pump pressure 2) Derive optimal orifice size as a balance of pump pressure, water velocity, and volumetic flow rate. 3) Define target die size. Heat load is basically unimportant. Assume 100W (real watts - not fake Radiate watts) as a peak 4) Determine what material you're going to make the waterblock out of. 5) Derive structural integrity constraints to cope with up to 50kg of pressure over a 1cm^2 area given the material you've chosen. 6) Machine the material in a way that maximises the water surface area within 2mm of each side of the CPU die (ie. for a 10x10mm die, target a 14x14mm area to maximise surface area over) 7) Using 2) above, derive a method to maximise the water turbulence over the die area specifically - this will be greatly affected by the design you've chosen in 6) 8) After 7), derive the maximum height required of the water-block material and the base-plate thickness. These two are linked more strongly that one would first imagine. Determine this for your 100W heat load. Target the fin/channel/block height at the 98% dissipation mark. Meaning that 98% of the heat is being dissipated below that height. Basically this defines an upper limit to the useful height of the block. As a hint, for copper/100W/water, if you're focussing on anything above 8mm, you're going in the wrong direction, unless you have pathetically low flow rates/pump pressure. After you've defined 8), you'll then learn that this impacts on 7), and almost always on 2), so you'll need to reiterate the process to refine it, while will undoubtedly bring 6) back into the mix as well, while keeping a very close eye on 5). Keep refining and reiterating those points and you'll asymptotically approach the limitations of the waterblock's efficiency with the design architecture and machining method you've chosen. I've been doing this reiteration process and managed to squeeze even more performance out of my design, but I'm also rapidly approaching the limitations of what can be done with the machining equipment I have access to.