I need a little help... I'm testing out my ATX system to see how much wattage / amperage it is drawing so I can make my final decision on which power supply to buy. I believe I am doing this correctly but the numbers seem a little weird to me. I took an old ATX connector and stripped off two small sections about 2 inches apart on each of the wires which i wanted to measure current on (-3.3vdc, +3.3vdc, +5vdc, -5vdc, -12vdc, and +12vdc).
Now on to my mesurements I started my computer and started up a dvd to try to get a pretty decent system load going. I then proceded with my multimeter to test each of the wires by switching it to the 10A symbol for testing amperage/current and cliped the alegator clips on each of the stripped parts of the wires individually as follows
Now comes the fishy part....
+3.3 = .07 A = .23W
-3.3 = 0 A = .00W
+5 = .05 A = .25W
-5 = .00W
+12 = .01 A = .12W
-12 = .00 A = .00W
Now i know that this is not correct but can someone help me correct my problem.
nope, he hooked it up wrong.Originally Posted by marshallh
the multimeter has to be in the circuit, not alongside it
so you have to cut the wire and connect each othe the probes to each of the wires
I should not have to cut the wire to test this should I? I mean cut the wire between the two ends of the multimeter
well, it might be the only way to do it. But it would be better to simply post your compoents and let us have a rough guess at how much your PC would draw, rather than going through the complexities of measureing amperage...
Sorry i was posting at the same time ... if i don't cut the wire i was just reading that i could just multiply the number of amps by 2 right because there are two paths for the electricity to follow.
Is this correct
Ok that seemed to give me some better numbers... one more question to caculate the total being pulled off the rails do i add up each of the +5v wires for instance there are 4 +5vdc wires which are red in a ATX connector would i multiply the amperage by 4 to get the total amperage or is calculating one wire sufficient?
My new numbers are still weird?
Orange 3.3V = .28amp = .92w
Red +5.0V = .28amp = 1.4w
Yellow +12V = .25amp = 3w
By the way im probably going with opus however, i would still like to calculate it myself