Power Supply Questions

[Dog--]

So Me and my teacher were cleaning out the old computer balcony type thing, and we found a whole bunch of old useless stuff the school got when they were new (back in the 80's), so there is all these old floppy drives, disc drives, monitors, keyboards, etc.

But I found a box of power supplies 400W each, and mine is only 300W, my teacher is going to recycle all the monitors and drives and stuff anyways, so I asked him if I could take one of those power supplies and he said I could.

So how do I know if it's safe? Can a faulty power unit break/blow up my machine? I want to know if it can do anything bad, and how to test it to see if it's good.

A little off topic - The reason I want more power is because currently my video card requires 350W but my current one is only 300W so I don't think I'm getting all the juice I can for it. 400W would do me well. Otherwise I wouldn't even ask nor would I even take a power supply in the first place.

Thanks, guys.

 

[No Limit]

How many amps does the 400W power supply have on the +12V rail? How many amps does your current power supply have? Just because you have 100watts more doesn't mean it will be any kind of benefit to you if the current rating on the 12V rail isn't higher.

To answer your question yes, a bad power supply can damage your computer. And there is no really easy way to test it. Do you have a DC volt meter?

 

[Dog--]

There are tons of them with all the other computer shit ready to be recycled (it used to be a computer science class, but the class was scrapped a long time ago and the just left all the shit there, so if you think we have if, we probably do). I don't know how to use it, though.

 

[No Limit]

Well first find out if it's even worth the risk. If your 12V rails are about the same in current output (amps) it's not worth it. This information is found in a table on a sticker on the side of the power supply. A lot of older and cheaper power supplies will increase the output on the 5V rails so they can rate their wattage higher, in reality this doesn't do you any good since the video card, the cpu, and other power hungry devices run off the 12V rail.

 

[Dog--]

So what would I preferably want to see when looking at the chart on the side of the power supply?

I didn't really look at it, but I remember there was a chart and I remember seeing like 2V, 3V etc.

 

[No Limit]

You will see a table that will have various voltage (+12V, -12V, +5V, and +3.3V). AUnder each voltage will be the current rating in amps. Look under the +12V column and compare the 2 values on each power supply. If they are virtually the same it will not be worth risking your PC for this.

If the 400W has a significantly higher rating on the +12V rail then it might be worth your time. Does this old computer lab have any old computers you could plug this power supply in to first?

 

[Dog--]

Well should the numbers under the +12V column be bigger or smaller then the others?

Also yes - Several old shitty PCs are among the crap being recycled.

 

[No Limit]

Well should the numbers under the +12V column be bigger or smaller then the others?

I'm not sure what you mean. On your old power supply you will have a current output under the +12V label. You will have a different current out put on the 400watt power supply under the +12V label. Compare the 2, if the 400watt power supply has a +12V current output quite a bit greater than your 300W power supply it will be worth the upgrade, if it's about the same I wouldn't waste my time.

Also yes - Several old shitty PCs are among the crap being recycled.

For sure plug this power supply in to one of those old computers first. That will be the easiest way to test it.