Please provide info on the power supply fan.

[Szech]

If you've read some of my posts lately, you'd know that computer noise has been thoroughly driving me nuts.

Well, my power supply is a noisy POS. I want to take out the current fan, and replace it with a low noise 120mm. I figure the airflow should be a lot better, and cooling should not be a problem.

I've ripped fans out of power supplies before, but I've never tried using the power supply after. Do I need to connect the bare contacts? Should I put a resistor on there? So the power supply thinks a fan is still connected?

Thanks http://www.sysopt.com/forum/smile.gif

[narayan]

If I understand your question, the fan inside the power supply will have a plug on it, so just plug your new one in.

[jad1097]

If not just cut and splice the wires.

[Szech]

Well, I was planning on running the 120 fan on 7 volts (5 if it will run right). The internal power supply's fan connector only has two wires, red and black, so I can't go that route.

I think I'll just make this one a trial and error thing though, so I'll post back with results.

[Graham]

Szech,
You could pick up the +12 and +5 volt lines inside the psu, to get your 7v, but I would <u>NOT</u> recommend it, there are lots of high voltages and frequencies in there. You could also run 7v from a drive plug and feed it into the PSU, but I would not recommend this either.
Simplest answer is to get a replacement fan, a quiet one, or put one running at 7v on the outside of the psu.
If you must use 7v inside, be very carefull, it should be easy to identify the +12 and +5v rails, they usually all terminate in the same place. Yo will not need to connect anything to the original contacts.

REMEMBER THE PSU CAPACITORS HOLD A HIGH VOLTAGE CHARGE FOR A LONG TIME AFTER YOU TURN IT OFF !!!!!!

[Szech]

Thanks for the heads up Graham.

I was planning on mounting the fan externally (on top of the power supply, blowing in), as opposed to trying to fit it inside the casing.

About the voltages... Would 5 volts be safer? If the fan operates properly on five volts, I was planning on doing so. I'm assuming that a 120mm fan running on 5 volts will put out more air than the 60mm fan running on 12. For powering it, I was going to use tap connectors to wire the fan to the red and black wires inside the unit before they go out to the drives and such.

As for safety, I have already unplugged it, and I plan on cutting the fan hole and mounting the fan after finals (probably Saturday or Sunday). I will also wear rubber gloves when handling the power supply.

One concern of mine was that the casing provides shielding from the frequencies that the power supply produces. I'm curious if cutting a 120mm hole in the casing would be a problem for this. I have another ATX power supply that has the fan on top blowing in, and it has metal guards, so I'm assuming that if I put a grill on my 120, it should be okay.

Good?

[captpete]

You should consider your psu a throw-away item. If it is the one that came with the computer, it is probably not that good even when new. Cheap psu's get hotter because they have cheap, light coils and need more fan and thus make more noise. A good psu probably weighs twice what you've got with good, substantial windings, and only goes in the range of $50. Plus it is so much safer to simply replace it.

[Graham]

Szech,
If the fan runs reliably and pushes enough air, you could use 5v (just be sure it starts everytime).
if the problem is that the original fan was too noisy, why not just replace it?
The psu's for pc's are all(?) switch mode, and as you realise can produce rf radiation. This may not be a problem , but to be on the safe side, you could....

1. Make the cut-out a series of small holes (0.25 in ? smaller the better) close together. This is the principle used on microwave oven doors.

2. Cut the hole out and cover with a metal mesh (you can get it in all sizes and metals)

3. Chance it, you should do no harm, and if it is a problem, change it later.

4.Get another psu with a quiet fan ( not my preferred option, I like to tinker/ make do and mend)

Options 1 and 2 could produce wind noise (from the fan, you understand http://www.sysopt.com/forum/smile.gif ).

What ever you do make sure nothing can fall into the psu, that could be dangerous.


Take care, and good luck with the final !!

G