question about voltage

[Jayfaas]

I have been having problems with a computer and i kind of suspected that it was the psu, so I pulled it out and hooked it to a motherboard, hard drive, and floppy, and I put the volt meter on it. On the yellow and black wires(12V) im getting a reading of 17! on black and red(5v) im getting 7, and on the orange and black(3.3) im getting 4.5. Do you think this power supply is bad and causing it to give too much voltage or is this normal?

[mpilchfamily]

Something isn't right there. If the voltages are really that high then the system would be burnt out. Check that you are reading the meter correctly. What meter are you using? Is it analog or digital? With voltages that high you would have burnt out resistors and blown or leaking caps on the motherboard.

[Jayfaas]

well im not sure how its working but I also checked the ultra x-connect 500w in my computer right now and used an extra 4pin molex to check the 12v and 5v and the 5v is more like 6.5 and the 12v is 16 and it runs fine so something is wrong here. The meter is a digital ECG DM-37

[Polizei]

For future reference, the black is not 3.3v. The black is a common ground. Orange is 3.3 IIRC.

[Jayfaas]

I know. I said orange and black at the top. Reason I decided to check the psu is because my brother let the computer sit for a few months, and then when he tried to turn it on it said "error loading operating system" and after trying all the things I could find on google to get around that or fix the problem, I just formatted it, and now I cant even get it installed. I fdisk'd the drive and it only read like 13 gigs or so when its a Maxtor 80gig sata drive, then when I tried to install on it it kept having problems and finally i got through the installation but then sometimes when I start the computer, it'll completely act like there is no hard drive and proceed to try to boot from the cd and when it cant it says "disk boot failure. insert system disk". and with the antec 350w psu in there, if I turn the computer off, I cant turn it right back on, I have to cut the switch off on the back, and then back on in order to get it to boot up again. any suggestions? What are some ways I could get to the bottom of this to find all the faulty hardware? He has:

Epox 9npa+ultra
MSI 48x cd rw
acer 56x cdr
floppy
Athlon64 3200 2.0ghz
1gb kingston ram(2x512)
80 gig Maxtor 6L080M0 hard drive

Any help is appreciated. Thank you