Power Supply?

How can I tell how many volts my computer power supply has?
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A DC voltmeter can be connected to the four terminals in any spare drive power connector.  You should see around 5 volts DC between red (+) and black and around 12 volts between yellow (+) and either of the two black wires.

Most of these power supplies need to have a load to properly work, I.E. they won't work without something other than a meter plugged into them, but usually the power supply fan is enough load.

Also try this test with the whole system running if you thing you have a power supply too small in wattage.

The orange wire in the motherboard connector (Pin#1) is the power good signal to the computer it should read 5+VDC to the black common ground wires.
rcloydAuthor Commented:
I am told that in order to upgrade to an AMD K6-3 450mhz Cpu. That I have to have a power supply that can deliver 250v. This is what I'm after.
the voltage put into a power supply from the mains voltage varies from about 230 to 250 volts ac. The power supply in your computer converts it to a variety of voltages which it dispenses through the various power leads. it puts out +12, -12, +5 and ground (0volts) the thing you need to look at is the power output of your power supply unit, the output voltage will always be the same, but components, such as yout hard and floppy drives, cd drive(s) and mother board, etc will draw different amounts of current. you need to work out how much power you are drawing
here is a list of roughly what each component will draw

3 1/2" hard drive                                                       5-15Watts
5 1/4" hard drive                                                       15-30 Watts
3 1/4" floppy drive                                                     5 Watts
5 1/4" floppy drive                                                     10-15 Watts
cd-rom drive                                                             20-25 Watts
1MB of memory                                                          5 Watts
monitor(if you run your monitor from your powersupply)     35 Watts
motherboard                                                              20-75 Watts
pentium CPU                                                              35-40 Watts

Add up the amount of wattage you will be using and compare with the "wattage" not voltage your power supply puts out. It's usually written on the side of the power supply.

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