Need your input on a waterblock design

[xenophek]

Ok, I think I'm going to machine my own GPU waterblock for my 4850. I'm sick of incredibly high temps, and I want this to run on ice. I have the equipment to fabricate the block (machine shop), and I have a handful of cars I could steal a heater core out of.

Anyway, I'm building a water cooling system on the cheap, and I need your advice on a potential waterblock design. What do you think:

[ame]http://i23.photobucket.com/albums/b367/Xenophek/4c2608ac.png[/ame]

Also, I'm having trouble narrowing down the material I want to use. I know copper is the material of choice, but it is a PITA to machine. For you water cooling guys, just how big is the difference between copper and aluminum? Enough to make it worth my while? Also, which material is more resistant to corrosion?

Right now I'm leaning toward aluminum, because I move around a lot and take Betty with me.

 

[jeod66]

Copper has just under twice the thermal conductivity of aluminum, which makes it transfer heat a good deal better. However, with good thermal grease and constant flow, I'm not sure that you would have any real problems with aluminum.

Corrosion caused by water will not affect aluminum at all; the most it would do is have a thin dull finish due to aluminum oxide. As for copper, given your time frame, it "shouldn't" matter. Copper pipes corrode because of garbage in the water lines over years and years of exposure, generally. It's not like you would be running acid in the lines, so corrosion should be a nonfactor.

Make sure you have all of the critical dimensions shown on that drawing; I tried to price out pieces of material and guessed at 1/4" inch thick. Now, I'm not a metallurgist, but my best guess would be that you'll want a "purer" alloy of aluminum. That would probably be either 1100 (99%+ pure) or 3003 (higher strength, less purity). They also have the benefit of being even easier to machine than the commercial alloys like 6061, 2024, and 7075.

 

[Stinky Wizzleteats]

Agreed, copper is the better choice for the contacting plate, also I'd avoid using actual water in the system because 1) if it ever leaks it'll more than likely ruin the entire computer. and 2) even with distilled water due to the warmth and moisture of the system, you'll likely get algae of some sort that will grow inside, which can kill your pump.

 

[Deacon]

Copper has always worked for me. Just to be clear, I would not try to cool your PC w/ tap water. Use a non-conductive liquid only. If you spring a leak and you're using water you will fry your system where as de-ionized water mixed w/ anti-freeze or some other name brand coolant will work better. That takes care of Corrosion issues as well. You may have to flush the system every 6-9 months, but you should do that anyway. It will be more efficient and will not short out your components.

Also, decide now if you want a low or high flow system. They both have pros and cons. I prefer the low/slow flow. IMO those have fewer leaks and better MTBF on the pumps used.

 

[xenophek]

Also, decide now if you want a low or high flow system. They both have pros and cons. I prefer the low/slow flow. IMO those have fewer leaks and better MTBF on the pumps used.

I guess low flow, since I move around a bit more than your average water cooled guy. Is my design alright for low flow or is there a particular pattern that is more suited for it?

Also, I plan on using a fishtank/fountain pump because they're cheaper. I can't make myself spend the money on a Swiftech pump.

 

[jeod66]

Agreed, copper is the better choice for the contacting plate, also I'd avoid using actual water in the system because 1) if it ever leaks it'll more than likely ruin the entire computer. and 2) even with distilled water due to the warmth and moisture of the system, you'll likely get algae of some sort that will grow inside, which can kill your pump.

Well said. I just assumed that you wouldn't use tap water (at the very least) in a system like this. Antifreeze/ethylene glycol has the potential to work well, but make sure that it won't attack your pump if possible. I suppose that a "nonconductive" coolant would be OK, but I personally wouldn't trust anything liquid and water based to be nonconductive.

Although, you could argue that true "distilled water" is nonconducting because it has no impurities to do so; however in practice it's incredibly hard to purify it that well from a tap source.

 

[xenophek]

Thanks guys. While I'm at it, I think I will go ahead and machine a large plate to act as the heatsink for the video card's memory or maybe include it in the loop, but I don't have any good schematics for the Radeon 4850 video card.

Does anybody know where I can get a good blueprint or something? I'd rather not take my card out.