Passive cooled opteron, borderline temps

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Passive cooled opteron, borderline temps

Post by goatee » Thu Sep 23, 2010 12:01 am

My previous machine was noisy, and I found myself using it for music production. Obviously not good, so...

I've built a machine, completely passive cooling with a custom (from scratch) case. Open top, big vents at the bottom, aluminium.

Can't find the camera so mockup at www (dot) foolswood (dot) co (dot) uk (slash) dumpground (slash) 4lk.jpg (first post so no links)

It is 50cm high, 55cm deep and 24cm wide.

Silverstone Nightjar 400w psu
Opty 2423 (55w tdp) w/ Thermalright HR01-X
Tyan mobo (amd SR5690 chipset) w/ Thermalright HR05-IFX
8G ram
Kingston vnow ssd (still to add)
I have a geforce 210 (to add)

In the bios temp monitor, the cpu settles at the 54/55C boundary and the northbridge settles at 61/62C.

You can feel the airflow it is generating well before these temps.

It seems a bit too warm to me. Any ideas?

p.s. I have been offered free peltiers, if that stands a chance of working.

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Post by bonestonne » Sun Sep 26, 2010 8:34 pm

Those temps are a little on the high side, but do remember, the system is passively cooled.

If you added 500rpm fans, you would notice a definitely drop in temps without a huge addition (or very noticeable addition) of noise.

As for the peltiers, I can't say I know enough about them to say they'd make a difference.

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Post by AZBrandon » Mon Sep 27, 2010 9:56 am

A peltier adds heat. Yeah, it subtracts from the CPU side of the pad, but it adds to the heatsink side, which means in order to move, say, 50 watts, it will subtract 50 watts from the CPU side, move it to the heatsink side and have a "transportation cost" of 50 watts, so the heatsink will be absorbing 100 watts of heat in total. That is OK if you run a water cooler where you are going to transport that heat out of the case entirely. In a passive case all you're doing is raising case temperatures, effectively adding more heat with no good way to get rid of it. You could end up with higher overall CPU temps as a result.

Do you have any way to monitor temperatures while the system is running? I see you mention BIOS, and if you're running 55C in BIOS, you might be pushing 70-80 under full load from a real application. Bottom line is that if you're doing 55C in BIOS, especially for such a low TDP chip, I don't think your case has enough airflow to get the job done. About the only thing that might help here is if you can undervolt the CPU to reduce that power load further.

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Re: Passive cooled opteron, borderline temps

Post by goatee » Sat Oct 16, 2010 4:44 am

Temps in applications are lower than in bios (I think it is because the bios doesn't do stepping). So I am actually getting ~40c on the cpu and ~52c on the northbridge.

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