Using an 800w server power supply for a car amp?

[Craig Arnold]

so i bought a big old server case for $15 yesterday, turns out it came with a motherboard and power supply still in it, don't know if they work but i believe he said the motherboard was what went wrong with it and it looks to be in pretty decent shape. now a few years ago i had a 300w 2ch car amp running off an old 300w atx psu i had laying around and it worked ok, occasionally blew the fuse in the amp, no big deal, i had tons. anyways i noticed this server psu is different than an atx, i imagine it should still be possible but i dont know how. the psu is a Dell D800p-s0. it puts out 62.5A on the 12v rail. i noticed this psu has a 20 pin and a 24 pin motherboard connector and that's whats really throwing me off, on the 20 pin its just black and yellow wires with 1 grey and the 24 pin has 9 yellow, 3 purple and 12 black wires.

so is it possible?
how big of an amp would i be able to run (i just need a mono amp)? i have an infinity 1260W 300w rms 1200 peak
And could this use as much or less power than a old yamaha 6ch receiver that I'm currently using? I feel like I'm already drawing quite a lot of power and I'd rather not increase it
also any quick way i can test if it works? i have a multimeter in my garage but i dont really have any idea what pins to use

 

[WyomingKnott]

Dell has proprietary pinouts for their power supplies, and even weirder proprietary stuff in their motherboards. Unless you can find a pinout from Dell you will be pretty hard-pressed to find how to use this. Maybe patient experimentation with a multi-meter.

That's a pretty strange setup that you have.

 

[americanaudiophile]

The power output of the psu is 750watts (voltage x current). Your amp will work with it but will not produce max peak power since the power supply would be regulated to not produce additional current for short term loads.
As to the power draw your old receiver will have a wattage rating somewhere on the back (usually near the power cord). I would guess that the receiver will not draw as much as the psu.
You will have to explore the pin outs with your meter. If you can get inside the psu you might find some marking on the circuit board to guide you.

 

[WyomingKnott]

Be careful, though. If you get inside the PSU you can get electrocuted, even if it's not plugged in. Big caps in some of those.