My endeavour into silent computing part 1

[AgnusDei]

Hello to everyone! Although this is my first post I have been many times here reading articles and hoping to make one for myself soon...

My current system is a Shuttle XPC wiith AMD Barton +2500/2 GB Ram Geforce 6600GT and a Samsung 160GB. Unfortunatelly there wasn't anything I could do to silence it since the main perpetrator of the disabling noise is the small fan in the PSU that spins at high revs producing an excruciating high pitched noise. I didn't want to invest any money on this old machine and I decided to look for alternatives.

All I needed was a quiet system with enough power to get on the internet, do some office and watch a movie or two. Solutions from VIA although highly attractive were to expensive for my budget (400+ Euros for a new system) On Ebay you can find used Via Mobo+CPU but often they reach 150 Euros and you still have to buy HDD or memory to make it work.
Next I thought of acquiring a second hand Pentium III system that could run without requiring a lot of fans or even fanless. After all a Pentium III system offers more computing power per Mhz than a C3 cpu at the same clock speed.

Searching on Ebay I encountered 3 possible candidates. Compaq iPaq "Legacy Free", HP e-PC, and IBM Netvista. All three of them can be bought from 25 to 100 Euros. The iPaq and the e-PC have only one fan, the Netvista has two (PSU and processor).

I found the iPaq more attractive to my taste so I got myself a PIII@733+256MB Ram+20GB Hdd+DVD-ROM. Final price was 104 Euros (postage included). The system that I got was in an excellent condition the inside of it was dustless and well kept. It has a very clever design thermally isolating the HDD from the mainboard and the single fan is placed directly to the side of the CPU Heatsink and sucks air directing it through the PSU to the environment. Unfortunatelly the 80mm fan was producing a rather irritating noise so I decided to replace it with a silent alternative. The problem was that it was placed inside the PSU so I had to open it and removing it by cutting the wires as close as I could to the blades. I am now in the process of buying a new fan. As soon as I have it I will post more information.
Thanks for reading!

P.S. Any suggestions for a replacement fan would be highly appreciable.
To change Euros into Dollars divide by 1,30


The internals after the HDD attached to its panel has been removed


Detail of the fan+psu


PSU removed


Fan severed

[IsaacKuo]

That's a nice, big CPU heatsink! You should give that 80mm fan a fair shake by seeing how loud it is when undervolted to 5v. You can also flip the fan to blow into the case.

[AgnusDei]

IsaacKuo Thanks for the reply.

I forgot to mention that the fan wires are buried deep into the psu soldered somewhere on the psu board. I don't think that I could undervolt it....Anyway the fan has been cut away.

There is a fan connector on the motherboard I believe I could connect the new fan there and perhaps undervolt it as well!

Blowing towards the case that might be a good idea I am concerned though that it will blow warm psu air towards the cpu plus all the dust will be coming in too.....

[IsaacKuo]

Oh, the dust will come in either way! But my experience with bottom mounted PSU's blowing air upward into the case is that the rear grill acts like a dust filter. Sure, the holes look too big to make for a dust filter, but just give it a few days/weeks. In short order, the rear grill will be covered in fuzz which blocks most of the dust. The best thing about this dust filter is easy cleanup--just wipe your hand across the back of the PSU!

As for the ease of undervolting--the internal PSU power connectors are irrelevant. They're going to be either 12v or thermally controlled anyway. If you want 5v power lines, the easiest way to get them is from outside the PSU. It can be as simple as poking a couple bits of solid core wire into a 4pin floppy drive power connector.

My favored modification is to wire a fan to a spare floppy power connector (ripped from an old dead PSU). I attach this power connector to one of the working PSU's floppy power connectors via two short pieces of solid wire. Red and black is +5v and ground.

[IsaacKuo]

Wait-a-minute. I just noticed that the fan was already set to blow upward into the case, in its stock configuration! I was wondering why the PSU was placed on the bottom...with the typical PSU configuration blowing air out of the case, the airflow would have been upside-down compared to the typical "warm air rises" theory.

But sure enough, the stock fan was showing the "wires/label" side on the inside of the computer. This is the "exhaust" side of the fan, meaning it was already oriented to blow warm PSU air upward at the CPU heatsink.

Nice design, I like it! Typically, a PSU generates a bit less heat than a CPU, but it's also less tolerant of higher temperatures than a CPU. Thus, it makes more sense to give the CPU warm air than to give the PSU warm air. I actually use this principle in a few of my custom computers, but this is the first time I've seen it in a stock computer.

[AgnusDei]

Thanks again Isaac you opened my eyes. You are right it makes sense to blow air upwards the upper cover of the case is a grill... Thanks also for your tip. I am not sure I understand it though I will try to buy a really silent fan hoping that I won't have to do any modifications. I don't have much spare time to try many thigns nor the proper tools.
I use a multipurpose swiss-army like screwdriver. The reason for that is that I am away from home and will stay only for few months in my present location. I just couldn't bare anymore the whine of my main computer....

[frostedflakes]

You can get older SFFs on eBay pretty cheap, and they are plenty fast enough for web browsing and other basic tasks. Congrats, sounds like it will be an excellent system for your needs. Let us know how the fan swap works out.