Voltage finder

Yo-Yo

Yo-Yo

Member
My power supply has 12V+ 15A on the sticker and on 12V+ 18A on the website. How can I find out which one is correct. I need to know if a certen video card will work.
 
use one of these, however they only test voltage and not load

multimeter.jpg
 
Do NOT try to use a multimeter to measure current on a PSU. I'd generally be inclined to trust the label, unless the website posts an explicit correction. Which PSU is it?
 
Well, you can download Speedfan and it will tell you the voltages on all of the lines...whichever one it is closer to (15a or 18a) you will know which it is.

However, both are pretty crappy, and I'd suggest getting a new PSU...even an el cheapo.
 
computermaineack said:
Well, you can download Speedfan and it will tell you the voltages on all of the lines...whichever one it is closer to (15a or 18a) you will know which it is.
Click to expand...
Guys ... there's a huge difference between voltages and amperages. 15A and 18A are amperage ratings for the +12V rail. This is not the same as the actual voltage on that rail, and cannot be measured via software.
 
ceewi1 said:
Do NOT try to use a multimeter to measure current on a PSU. I'd generally be inclined to trust the label, unless the website posts an explicit correction. Which PSU is it?
Click to expand...

IME, multimeters give the best voltage results. Going off the label is just putting blind faith in a company. Even though that a multimeter does not test a load of power it will at least give you spec voltage. You must realize that its not an exact science and a lot of things are put on paper for marketing reasons. I can't tell you how many times I have tested a power supply with a multi meter and gotten results that are off spec. Like I said it will test voltage to the T, but it will not test a load, for that you need a higher end device however is your PSU is not outputting spec voltage a multimeter will definitely pick it up.

A lot of PSU companies will post their optimal wattage for a PSU but it does not include a load test. That is typically due to trial and error. If a PSU is giving out bad spec voltage, the multimeter will pick it up.
 
I am very much aware of the dangers of blindly trusting manufacturer specs, which is part of the reason I asked what PSU he had. What I was referring to in my previous post was attempting to directly measure a PSUs current output by hooking a multimeter in ammeter mode up to it. This will not work, and is in fact very dangerous to the supply.

It's true that excessive loading will often cause voltage drops on the PSU, but do realize that this is not a symptom that is guaranteed to manifest itself. Supplies loaded beyond their maximum capabilities may fail over the long term, particularly as the capacitors age. They may also blow without significant voltage drops.

Certainly voltage readings are helpful, and if they drop too low it's time to replace the PSU, but a reading that's within spec doesn't guarantee anything.
 
tlarkin said:
use one of these, however they only test voltage and not load

multimeter.jpg
Click to expand...
Would I just unplug the line from the mobo and connect it to the two wires? I am assuming that the plug shaped like a square with 4 boxes is the 12V thing. The only problem is the only multimeter I have maxes out at 10 amps.:mad: I also tried speedfan and It only said My 12V+ was running at 12.05V
 
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Yo-Yo said:
Would I just unplug the line from the mobo and connect it to the two wires? I am assuming that the plug shaped like a square with 4 boxes is the 12V thing. The only problem is the only multimeter I have maxes out at 10 amps.:mad:
Click to expand...

The only thing I use a multimeter for is to test spec voltage, and if you don't know how to test one I would probably not recomend doing so, I unplug them from the machine completely and manually ping them on with a paper clip and then test the voltage of each connector to make sure its near the +/- 5 and the +/- 12 range. I have a cheap one that only handles like 20 amps so I don't do any of that. Typically IME if a PSU is bad it will spit out random voltages, or out of spec voltages. You can deven toss a few devices on it and test it (like optical drives and HDs) and see what voltage it tests then. I would not suggest testing it with a mobo and proc.
 
Another question that is why I needed to know the amps is if a 7600gt would work at its full power at 15 amps. My power supply has 400 watts. (Another thing I found is my power supply on newegg says 18 amps. That makes 2 for 18 and 1 for 15)
 
ceewi1 said:
Guys ... there's a huge difference between voltages and amperages. 15A and 18A are amperage ratings for the +12V rail. This is not the same as the actual voltage on that rail, and cannot be measured via software.
Click to expand...

Woops...the title said Voltage Finder, and I'm tried and stressed.........
 
Yo-Yo said:
Another question that is why I needed to know the amps is if a 7600gt would work at its full power at 15 amps. My power supply has 400 watts. (Another thing I found is my power supply on newegg says 18 amps. That makes 2 for 18 and 1 for 15)
Click to expand...
Newegg just get their specs from the manufacturer, but it could quite possibly be right. Could you please post a link?
 
hehe, I should have looked at your sig first :)
If your PSU will handle the X600, it'll handle a 7600GT.
 
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