PSU Passive Cooling Conversion

Solid Snake · Post by **Solid Snake** » Tue Nov 16, 2004 6:12 pm

I noticed that it's almost impossible to have a fanless PSU run at a decent temperature, the heatsinks are so dinky. Since I'm a DIY amplifier freak, I have lots of massive heatsinks laying around. I was thinking of cracking open a standard ATX PSU, chucking the fan, getting a bunch of TO-220 mica insulator kits from RadioShack, extending the active devices from the board with wires and mounting them to a massive heatsink, then heat shrinking their terminals and grounding the heatsink for my protection. Of course this mod would take up more space than a standard ATX PSU but it should make for a silent PSU with a higher-than-stock MTBF. What do you guys think?

ddrueding1 · Post by **ddrueding1** » Tue Nov 16, 2004 6:36 pm

That sounds darn cool to me, but why not get one of the passively cooled PSUs to begin with? They say you need some active cooling around them, but extending those heatsinks would likely aleviate the problem.

Solid Snake · Post by **Solid Snake** » Tue Nov 16, 2004 6:55 pm

So they call them passively cooled PSU's because they ship without a fan but they need a fan anyway? That sucks.

ONEshot · Post by **ONEshot** » Tue Nov 16, 2004 8:39 pm

sthayashi · Post by **sthayashi** » Tue Nov 16, 2004 8:42 pm

Passive PSUs need airflow or at least cool air. The manufacturers assume that you have some airflow in your computer (not an unreasonable assumption, IMHO).

ddrueding1 · Post by **ddrueding1** » Tue Nov 16, 2004 8:45 pm

I certainly agree that the fact the fact that all the "passive" PSUs need a fan is stupid, but you need to regocnise that they were stuck with fitting a certain form factor. If conforming with this form factor while providing "passive" cooling required some airflow, I can't really blame them.

However, it does provide the "hard core" modders with a great starting point to truely passive mods...

-pui

lm · Post by lm » Wed Nov 17, 2004 2:14 am

There's an article on sprc which does just that... power supplies/Marko's homebrew.

larrymoencurly · Post by **larrymoencurly** » Wed Nov 17, 2004 5:04 pm

The stock heatsink with the high voltage transistors on it may be at high voltage even if the transistors are electrically insulated from it. I read somewhere that this is done to ground out EMI without making a direct connection to earth ground, in case the PSU is operated without a ground connection.

Solid Snake · Post by **Solid Snake** » Fri Nov 19, 2004 7:11 am

I'll be operating with a ground. The big heatsink will be tied to that ground and the transistors will be isolated from the heatsink.