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PSU failure

Last response: in Components
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February 15, 2003 3:48:44 AM

I have this PSU i got from a pentium system. It didnt say the wattage on it so i calculated how many watts and got 310. (i did the calculations 5 times, so i know im not wrong). I've had it in my Athlon XP 1800+ system for almost a year and havent had any problems till now. I have my CPU fan hooked up to the 7.5 DC line from the molex four pin connector and the other day my system crashed and when i checked cpu temp, it was 73 C. The reason? The 7.5 volt DC line (on all molex connectors) was putting out 5V DC instead of 7.5, causing the fan to spin at a considerably lower rpm, allowing the CPU to overheat. I am planning on buying a new 300 PSU tommorow but I am wondering if there is any way to fix this, and just wondering if anyone else has had a similar problem. I also have a Maxtor 7200 ata133 40 gig hdd, ATI Radeon 9500 Pro, 40x sony burner, zip drive 100, tv tuner card, modem, and 5 case fans.

Thanks,

14D

If its not broken, you're not trying hard enough.

More about : psu failure

February 15, 2003 9:58:29 AM

There is no 7.5V line on PC PSUs. Only 12V, 5V and 3.3V (negative voltages are useless). You can only connect a fan to a 7V potential difference line by connect the positive wire to the 12V line and the negative to the 5V line.

My dual-PSU PC is so powerfull that the neighbourhood dimms when I turn it on :eek: 
February 15, 2003 10:40:41 PM

Yeah i just realized that, I guess my dealer but something else in whatever I was smoking lol. Got the new PSU and no problems, i guess the ohmage or amps was messed up on old one. It needed to retire anyway.

If its not broken, you're not trying hard enough.
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February 17, 2003 11:38:47 PM

Yes... and if it was a low quality PSU that was being taxxed all the time it would indeed die quicker.

<b>Anyone claiming they can see the difference
between 450 and 500 FPS in Quake3 deserves to
be severely beaten with a rock. :smile: </b>
February 23, 2003 4:23:45 AM

If you calculated the power to be 310W, then most likely this was a 250W or smaller supply because with ATX supplies the sum of the volts * amps is always much higher than the label watts. Its electrolytic capacitors probably just wore out from ripple current or heat from the transistors because an Athlon 1800+ is a fairly good load for the typical 250W supply.
February 23, 2003 4:41:07 AM

FWIW... Most fans are 12 volt.

The molex drive connectors are 5 and 12 volt.



<b>(</b>It ain't better if it don't work.<b>)</b>
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