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Power Supply Problem


New Member
May 24, 2007
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I have an Antec "Truepower 480". I have connected all the 12+ and ground wires together on a terminal strip, with shunts, so I can use the power supply to operate some 5 amp, 12V fans. I have grounded the green wire and the unit will turn on, with internal fans running, and registers 12V on a meter. However, as soon as I apply the small load of a fan the unit immediately shuts down. The fan will make about 1 revolution. If I wait a minute or two I can turn it back on, but again, as soon as I try to apply a load it will shut down?? I have tried running the gray, Power OK wire to +5V, but that doesn't help? What do I have to do to get power out of this thing?


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Is your PSU only powering fans or is it fans and your system?

Also, what are your system specs.
You can expect people to help you with soo little information.


New Member
May 24, 2007
3 (0.00/day)
HMmmmm. I thought I made it clear that I have reconnected all the wires to terminal strips so I can use the power supply simply for the purpose of powering a couple of 5amp fans. Nothing else. The 480 is supposed to handle 20 amps at 12V. There is obviously something I am missing in the wiring of sensors or??????

I was hoping someone here had converted this or similar power supply, for bench use, and could help resolve the problem.


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those fans may run at 5 amps but on start up how many amps do they draw?

the higher the running amps are the higher the starting amps draw will be over running amps.
Apr 10, 2007
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Central FL, USA
those fans may run at 5 amps but on start up how many amps do they draw?

The higher the running amps are the higher the starting amps draw will be over running amps.
A little known and seldom talked about FACT is that the rated wattage of any PSU is the Maximum Peak Current (that it takes to charge the caps on a motherboard, in a few split seconds).
Derate that number by 25% to 30% to get the all day running amperage. I know you said it's an "Antec 480 truepower" but even those have a max peak power value that must not be exceeded if you expect the supply to fully boot up.

Flatjwl, did I miss something or did you NOT say how many fans you're trying to run off of this supply :confused:

It's very possible that the startup current drawn by the fans, exceeds the max peak power rating of the supply. Just one fan, maybe not, but multiple fans.....most likely.

A series regulated supply would power through the overcurrent condition with hardly a whimper, but a Switcher will not. It will just sense the overcurrent condition and shut down. Exactly what you're seeing.

I've seen PC PSU's shut down just from adding an extra case fan to the system.:mad:

I used to design power supplies for Caterpillar Tractor Co., so I have a little more than a modicum of experience with them. The quality of PC PSU's really makes me kind of sick.:cry:

To run DC fans, all you need is a 12v transformer and a full wave bridge rectifier of about 20 amps. Or a 12v battery and a little trickle charger to keep it charged.
Using that Antec PSU to just power fans is a huge waste of technology.:banghead:

I wish you good luck,

The Shadow :cool: