Running a PSU passively

[Jimbo Mahoney]

Just after a second opinion on what I estimate is safe:

250 Watt PSU running P200 (passively cooled), 96MB RAM, 1 x 80GB HDD.

Estimating a worst case 125 Watt load and 75% efficiency, the PSU is consuming 125/0.75 = 166 Watts, which means it needs to dissipate 41 Watts as heat.

I reckon it can do this without a fan.

In reality, I suspect it's more like 50 Watts usage = 16 Watts needing dissipating by the PSU.

Whadya reckon?

(I'm trying it at the moment, keeping a 'feel' on how hot the PSU casing is getting.)

 

[shadowscotland]

my system at load only pulls 120watts at the wall - I think your numbers are off or if correct use a new chip.

If the case fans produce a airflow across/out the psu you may be in luck, but don't rely on the psu standard heatsinks - bolt on some more surface area. - look at how silverstone or yesico make their fanless psu's

Remember most PSU lose efficency with temp rise - so you may create a chain reaction if running passive.

 

[decto]

It takes very little airflow to make a big difference to the temperature of a heatsink. Removing the fan from an old PSU is a recipe for disaster. If you want silent running better to look for a DC -DC converter such as PICO power or a PSU designed to be fanless.

Another option is to fit a fan contoller to the PSU so you can slow the fan down but again this isn't recommended. Especially if you are planning to leave the system unattended.

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