View Full Version : Power supply

17-10-2006, 12:11 PM
Hi there!
I have PC with Asus motherboard A7V133, Athlon CPU and XP home. on this mobo three (3 !) power supply units failed. The last one gone like that:first green light was on, then it blinked then it went off with quiet click. After couple of restarts the green lamp finely did not glow at all.
I just wonder if there is some foult with the mobo?
Can it be that Ps is ok, because fans did work? Or there is some protection that trips?
Any ideas?

17-10-2006, 01:03 PM
Buying cheap quality PSUs?

17-10-2006, 01:42 PM
Now-w-w! Of course not! My PS is Thermaltake! And PSs' are ok! Installed them on other PC and the work all right. Then took PS wrom working PC and it did not work. So it is definetely the mobo. When it happened before, I change PS and it helped somehow. But the problem must have been not PS.

Any ideas?

Graham L
17-10-2006, 01:56 PM
Do the PSUs still work after being used with the dubious motherboard? There is a fuse inside which will blow if there is a major fault, but usually they just shut down if the total power demand is too high.

You have made sure the connector is the right way around? The old PC and AT PSUs with two connectors could be connected wrongly, with disastrous results, but you'd have to work at getting the ATX ones in the wrong way. However, dogged determination can work miracles. :D

If fans run, the PSU is working. An overload on the other supplies which come on later will shut down all the supplies.

17-10-2006, 02:53 PM
could be a short between the mobo and the case perhaps ?......try it with the mobo on a bench....

17-10-2006, 05:46 PM
This all began after I have swapped CPUs with other PC and installed 750 MHz one instead of the original 1.2 GHz. My guess is now that 750 MHz CPU became overclocked and might be dead as a result!
Is it possible?

17-10-2006, 06:03 PM
You should make sure the capacitors on the mobo aren't bad (i have seen bad caps that take out the PSU at the same time)...

See http://www.badcaps.net for examples...

17-10-2006, 07:32 PM
a dead/dying cpu shouldn't kill three psu's....

Pete O'Neil
17-10-2006, 07:36 PM
There alot of possibilities in terms of what could be causing your problems. Without a more detailed discription of the problem and circumstance surrounding it, it is unlikely anyone here will be able to solve the problem.

Your best bet is to take everything out of the case and test it on a workbench. Start with the minimum for the PC to post, if it wont post you can then start testing each individual componet. If the minimium require for it to post is ok then start adding things such as harddrives and optical drives.

That way you'll get a better idea what is causing the problem and we be able to provide the people here with more infomation.

Stop posing random ideas and start answering people questions. Do the PSU's work in other PCs after theyve been in the broken system? Take the motherboard out of the case to make sure its not shorting on the risers. Did you reapply thermal paste properly after you changed CPUs?

Depending on the motherboard you may have inadvertantly overclocked the CPU, if the motherboard uses dip switches to set the FSB and the two CPU run at different FSB's then it may have tryed to increase the FSB of the slower chip. But its unlikely this would kill the CPU, and would merely stop the system from posting.

18-10-2006, 03:32 AM
Thanks Pete!

The Mobo is originally AOpen AK73, not ASUS, sorry, with 1.2 GHz Athlon CPU. I replaced it with Athlon 750 MHz CPU. Has done this to give my PCU to somebody.
At first it worked, but after putting the compoundand restarting PC, green LED started to blink and went off. Screen was black but fans worked. Suspected PSU failure, but that PSU works ok on other PC.
Will do what you suggested, and also want to get another PCU as the original 1.2GHz, thus to solve the overclocking, if it is the cause.