What happens when a PSU is overloaded?

[Maximilian]

So say theres a 600w PSU and the comp starts pulling 650w, what will happen? Will it blow up killing everything around it or will the comp just shut itsself off?

Also can PSU's be overloaded for a short time? Like 600w PSU doing 610w for a minute etc?

 

[Red Squirrel]

Depending on the quality it might in fact handle it. Basically by overloading it you're just pushing it beyond it's rated spec. If it has a fuse, it might blow the fuse though. Some cheap PSUs might even blow below their rating if it's a continuous load.

 

[smackababy]

Ideally, the fuse will blow before anything bad happens. I think it will shut off once it hits a certain point beyond what it can handle though. Something like 610w being pulled on a high quality 600w wouldn't be too much of a problem. I've seen reviews where 750w PSU have taken 1000w before they shut off.

 

[Modelworks]

Its a crapshoot.
Once you reach the rated wattage it could do anything from shut down to burst into flames, just depends on that specific design.

 

[Puffnstuff]

Well most quality ps's can handle short bursts outside of their rated capacity. Cheap ones on the other hand...well just read any of the tests and you'll get the idea. If you plan on doing it just keep an abc rated fire extinguisher handy.

 

[thescreensavers]

Here is what happens when a chepo 400 watt is asked to put out 450 watts http://www.youtube.com/watch?v=-OgKFm-bv5k

yea, better quality PSU's will likely handle the power for a bit or just turn off.

 

[Red Squirrel]

Here is what happens when a chepo 400 watt is asked to put out 450 watts http://www.youtube.com/watch?v=-OgKFm-bv5k

yea, better quality PSU's will likely handle the power for a bit or just turn off.

haha that was pretty cool. That's also quite an impressive killawatt device!

 

[HOOfan 1]

haha that was pretty cool. That's also quite an impressive killawatt device!

It isn't a Kill-a-watt It is a SunMoon SM-268. ATE programable load tester.

You can get one too, for a few thousand dollars.

 

[Yellowbeard]

Its a crapshoot.
Once you reach the rated wattage it could do anything from shut down to burst into flames, just depends on that specific design.

Don't forget ripple current. As a PSU nears 100% capacity or as it exceeds its rating, it's going to start letting more ripple current (AC which is bad for DC stuff) bleed thru. So, over time this will damage the components in your system and kill them just as surely as an exploding PSU. It just takes longer. It's like a cancer as opposed to a heart attack.

 

[bryanl]

The supply should simply shut down, but one built with undersized diodes or transistors may have those components fail, usually by shorting. The transformer may overload, causing a drop in output that the regulator will try to correct but in the process overshoot the desired voltage and cause abnormally high output for a moment and can damage the rest of the computer. Good supplies can output far more than their continuous rated power for several seconds