Modding PSU to silence?

[Mephistopheles]

I've been messing around with a very old computer (Duron 1200 with 512MB memory on a K7VM2 Asrock mobo) and I want to make it completely silent.

Now here's my progress so far: I'm using an old but rather good heatsink that supports 80mm fans and I've done the crazy silence guy thing and tried underclocking the Duron to 600Mhz. Now it runs crazy-cool at below 40C with only a very, very slow (and ridiculously silent) fan on top of it. Unfortunately, I can't undervolt it through the bios. Is there a way to do that? A Duron 1200Mhz is rated at 1.75V, while a 600Mhz Duron SKU is only rated at 1.6V. If I could undervolt it, it would consume -20% power and I could probably forget about a fan (this processor is rated for up to 90C temperature).

Well, the CPU isn't the main issue: the PSU is, though. It's a generic-brand 450W PSU - pretty simple stuff - cooled by a rather noisy 80mm fan. I've been considering modding it with an Akasa Amber PaxPower 80mm fan which I already have, but I'm wondering if the cooling will be enough. Will it?...

Also, the fan header is soldered directly to the PSU PCB, so I'd have to improvise. The simplest way would probably be to connect it directly to the outside molex connectors, but I suppose I could also cut the wires and put the Amber PaxPower 80mm fan directly there. Would it be OK to put it on an outside molex connector? I'm lazy.

Also, if more cooling is required, I could go with a 120mm fan on top of the CPU, though that would require more improvising because 1) I don't have such a spare fan and 2) the PSU case doesn't have the hole for that.

What do you guys think? Is an Amber Series 80mm fan enough? Bear in mind that I'm running a pathetically economical system with onboard video, audio, network and an underclocked Duron.

Here's a picture of the PSU:

 

[Mephistopheles]

I installed the akasa amber 80mm fan and got a little more noise than expected from air turbulence inside the PSU.

So I then connected it to a spare Fan Mate 2 I had lying around and I then got... a ridiculously quiet system! 8)

Unfortunately though, I'm concerned that the reduced airflow will incur in excessive heating inside the PSU, and I don't even have the means to measure temperatures inside it. For my peace of mind, I could get the 120mm akasa amber fan and use it to blow air at 5V on top of the PSU... I might as well leave the PSU case open anyway.

Funny thing: I don't have a case for this computer, it's just lying around on my desk, piece by piece. But I don't want to have to buy a new case for such an old computer! I wonder what I'll use as a case... :?

 

[Mephistopheles]

Hmmm that's right, they might not work at 5V...

But I'm pretty sure that 1300rpm-rated 120mm fans spin up at 7V, so I could just try 7V: my main rig is a thermaltake armor with 2x120mm 7V-modded fans, and it works just fine.

The stupid thing is that we have no means of finding out how much cooling is enough, like we have with CPUs. I suppose I'll have to guess...

Is there anything else I could do? I'm thinking I could install some heatsinks on the side of the PSU case or leave it open with that 80mm fan running at 5-7Vish or so. I could also mod the heatsinks that arleady exist inside the PSU... Or put the 80mm fan directly on top of those. They are the components that heat up the most, right? I mean, they're directly attached to the voltage regulators...

 

[Mephistopheles]

I've tried running with the PSU case off and it worked. Heat generated is minimal: there's no hot air whatsoever around the PSU.

Kinda makes me think that this is all a little stupid: the PSU case is only really there for protection and modularity. Also, it's pretty stupid to mount this thing upside down: this is probably the reason you need a fan in the first place!

Anyway, I'm thinking I'll upgrade the heatsinks. Look at this:

If properly attached to the existing heatsinks (arctic alumina or something), this small aluminum heatsink (LxHxW: 28x16x15mm, very, very cheap!!) will probably help. I'll just take a few measurements and get some of these... and use the amber 80mm on the processor!

Besides the voltage regulators, are there any components that heat up? I could place heatsinks on top of any of these too!!!

My only problem then is that, after modding, this PSU must be used with the PCB oriented upright for passive dissipation. Meaning I can't use a regular case, so I'll have to... erm... manufacture a case for this stuff. :?

 

[ara]

Funny thing: I don't have a case for this computer, it's just lying around on my desk, piece by piece. But I don't want to have to buy a new case for such an old computer! I wonder what I'll use as a case... :?

my old retired SHOEBOX computer had a similiar problem... it's retired now though, didn't need it, i might get it as a folding box though it would be useless (k6-II)

only problem is that your motherboard has to be pretty small, like that one was, in order to fit in a shoebox.

Ara