More Radiator, Less Noise

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Roy Dennis talks about his homebuilt passive cooling radiator.

The overclocker’s enemy is heat. The overclocker usually blows away heat with fans. This works fine, except that the noise of six 120mm fans blows your ears away, too.

Even with watercooling using pelters and a heat sink, you usually still have a fan for that, besides the PSU fan and a few more here and there.

One way to get rid of most of the fan noise, but keep the overclocking is to use water cooling and large radiators.

I have designed a simple radiator that fits on both sides of the PC, (the bigger the PC the better.) It is simply two large copper sheets with sidewalls epoxied with araldite or better, then soldered in place, like so:

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The internal flow directors are rectangular pieces of copper glued to the copper sheets. Since they do not need to be watertight, I suggest that you smear araldite on one side and stick it in place (unless you have a really itchy blowtorch :-), like so:

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The hose barbs are placed by drilling a hole in the copper-plate and either aralditing or soldering them in place.

After this you may want to think about attaching them to your PC, which is a little more difficult. Cases are different, so you’ll have to think a bit about how to do yours, but here’s some general concepts and tips.

First, when you put in the flow directors, measure where you placed them, and WRITE IT DOWN !!!!! You write it down because when you’re mounting this after you’ve sealed this, you’re not going to be able to see where they are after the two copper plates have been sealed together.

After that, smear araldite onto the top of the flow directors (and the sides as well if your not going to solder the sides to the cover) and stick the other plate on top. If your not using araldite, solder the cover on.

You want your flow directors to be wide so you can drill mounting holes into the flow directors rather than the water channels. This is how you do that:

Take those measurements you wrote down, and figure out the center of the flow director where you want to place a mount.

Drill through the spot in your PC case where the mount is going to be mounted.

Cut a copper tube which has a slightly larger diameter than the hole you have drilled, and a larger internal diameter than the bolt you are going to use.

Cut the spacer to the amount of clearance you want between the radiator and the PC case (probably about 2-4 cms).

Now, the important bit. Epoxy the underside of the bolt head so the epoxy squishes out when you tighten the bolt (don’t tighten it yet).

DO NOT USE QUICK CURING EPOXY!!! If you do, it will all set before you’re done, which you will soon see is NOT a good idea.

Now press in the bolt. (This is not the time to take a break.) Put some more epoxy onto the bit where the threads emerge from the hole in the radiator. Do not be afraid to use plenty of it. This is what it should look like:

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Push the copper spacer in place. Bolt it all together and make sure the bolt moves AS LITTLE AS POSSIBLE.

Turn the nut and hold the bolt in place.

Complete each step to all the mounts before proceding to the next step. Don’t complete one, then start on the others, it won’t fit right. This is why you need to use slow curing epoxy.

It should end up looking like this (epoxy not shown):

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I haven’t given you dimensions because it depends on your system. I do suggest, though, that the actual channels end up having a definite rectangular cross section. Don’t bother with too many flow directors. Just make the channels wide and shallow.

Does this approach work?

Well, if you make two of these (cool-looking) things this way, they’ll have a large surface area exposed to a lot of air. With a compact radiators, made up of loads of fins with very little spacing between them, you need a fan to keep the narrow air spaces from simply heating up to the same temperature of the water, and not radiating the heat away. With a design like mine, the water temperature should be near ambient. If you make two (which I strongly suggest, especially for Athlons), you can have a cooling circuit like this:

Pump, Radiator 1, Processor, Video Card, Radiator 2, North, South (East or West) bridges, RAM, then back to the pump.

Ahhh, but how do you cool all that stuff?

I’ll talk about fitting RAM to this. Take a look around this website to find out about other connections.

RAM

This is neat; it’s simple and it works!

First, use thermal epoxy to attach a copper heat transfer plate onto the chips.

Then epoxy the coolant pipe to the plate. The ends have to bend by 90 degrees, so heat the pipe with a blowtorch, then bend it BEFORE epoxying pipe to plate.

The copper plate has a very low resistance to thermal spread so the coolant pipe DOES NOT have to go right from one end of the board to the other. That means you can have a large diameter bend at the end of the coolant pipe. This will prevent kinking (which greatly restricts waterflow).

It may not possible for another memory card to go in the next slot after doing this. You should (you can on mine) simply be able to miss a slot and bung the other in the next one).

Make sure at no point in the coolant system do you use a pipe that can’t handle the GPH rating of the pump or you’ll slow down the whole cooling system to the speed of that bottleneck. This means that in practice, you will probably only be able to get a very small amount of pipe onto the RAM board without kinking (which doesn’t matter because of the copper plate).

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All this will mean that hardly any heat will ever get a chance to get into the PC case itself. That means that you will only need the 80mm PSU fan. Since the case will be cool, you’ll probably be able to reduce the voltage on that to make it even quieter.

You should now have a quiet overclocked PC. Happy OC’ing.

Mail me if you have any comments or suggestions.

Roy Dennis

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