Bridging Heatsinks ...

[icenine0]

So I've got this 650W charbelcher of a dual Xeon system I run things on, and I've been looking at means to quiet the thing down.

I bought two bargain basement copper passive heat sinks designed for Intel servers, which is apparently code for "does not mount to anything else."

However, they almost work -- just a little tall. I'm wondering, if I buy a 3" piece of 1/8" thick aluminum to bridge the chips and close the height gap, what will that do to cooling efficiency? What we're talking about here is combining two individual heat sinks and heat sources into one fat heatsoaking system.
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[sephiroth111]

why not use watercooling? aside for the fact that its somewhat expensive
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[shawn]

I can't remember what they are called but there are these electronic cooling plates I'll refer to them as where they use no fan at all. I think they had a condensation problem with this but that was several years ago I read about them and that could very well may be a non issue with them at this present time.
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[icenine0]

I did use it for a long time, but I moved away from it.

First, the water evaporated and I nuked my pump (my mistake).
Second, it blew a gasket and soaked my system.

It worked very well while it worked--but I'm no longer sold on the idea of water + computer, no matter how efficient it is.

> why not use watercooling? aside for the fact that its
> somewhat expensive
>

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[icenine0]

Are you talking about http://www.heatsink-guide.com/peltier.htmPeltier</A> coolers?
They can get your CPU frosty, but they actually ratchet up the cooling
requirements. I'd need an even fatter heatsink + fan.

Maybe I should get a http://www2.asetek.com/default.asp?showPage=startside.asp&contentSection=2VapoChill</A>? <img src=smilies/magbiggrin.gif>
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[MasterHD]

I've actually built a TEC cooled system for a class project. We didn't put the peltier right on the CPU because of condensation issues, and rapid temperature changes when powered off. It didn't work as well as we had hoped. The main problem was that the pump we used was adding so much heat to our water cooled system, and we didn't have a large enough fan removing heat from the peltier.

As for connecting two heat sinks together, I don't really understand how you're connecting them, but any contact between two separate pieces of metal is where you'll have high thermal resistance. You'd have to put some thermal paste between them, or welding might work (???).
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[icenine0]

I was considering, more or less, the setup below:
(HS1 and HS2 = heatsinks 1&2)

<tt>
+-----+ +-----+
| HS1 | | HS2 |
| HS1 | | HS2 |
+-----+ +-----+
~~~~~~~ ~~~~~~~ <--- THERMAL PASTE
+-------------+ <--- METAL BRIDGE (COPPER/ALUMINUM)
~~~~~~~ ~~~~~~~ <--- THERMAL PASTE
==CPU1= ==CPU2=
</tt>

Peltiers sound very tricky to work with.
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[MasterHD]

> I was considering, more or less, the setup below:
> (HS1 and HS2 = heatsinks 1&2)

I don't see why that wouldn't work. Just remember to use as little thermal paste as possible. You want as much metal-to-metal contact as you can get. The paste is just supposed to fill in the gaps where there'd be air between two "smooth" metal surfaces. It won't cool as well as having the heat sink directly on the CPU, but it will help even out the loads. For instance, when one of the CPU's is running at 100% while the other was idle.
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[Cornellius]

> I don't see why that wouldn't work. Just remember to use as
> little thermal paste as possible. You want as much
> metal-to-metal contact as you can get. The paste is just
> supposed to fill in the gaps where there'd be air between
> two "smooth" metal surfaces. It won't cool as well as having
> the heat sink directly on the CPU

Well, you can put some thermal paste all over the surface, just don't use too much paste. With little pressure on the two parts with the paste in the middle, the thermal paste will stick the two pieces together and will help for a better heat transfer from one piece to another.
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[MasterHD]

Ah, yeah I may have made that sound confusing. Put thermal paste everywhere you had pointed out in your little sketch, just don't make the paste layer too thick. There's quite a bit of loss in heat transfer if you put too much.
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