Unit will not power up

[stucknok]

Hello. I am new to this forum and hope some of you experts can help with my problem. My son built his own computer last summer for college and it has worked great until last week. It started out freezing up and having to be rebooted. This has progressed to the point where the machine will not power up at all. I have checked the power supply by jumpering the common to pcon terminals and checking voltage at pins. All voltages are correct with the exception of the (-)12vdc pin which reads (-)11.3vdc. The fans will run with the common and pcon pins jumpered together. Something smells burnt to me in the case but I have had all the boards out and nothing looks damaged or burnt. The specs for the machine are as follows:

Asus A7N8X motherboard with AMD Athalon 2200 cpu
(2) Corsair 256mb DDR RAM / 333 MHZ
Radeon 9700 Pro video card
Xcase full tower with EB-500 power supply
Windows XP professional os


Any ideas or suggestion? I am wondering if the motherboard or cpu is bad?

 

[johnjkr1]

Simple troubleshooting steps. First, disconnect all unnecessary devices (keyboard, mouse, pci cards, hard drive power and data cables, one stick of memory, etc). Next, reseat what is left (the CPU (see if it is burnt while you are at it), the video card, the power connectors). Then reset the cmos using the reset cmos jumper. Turn it on and see what happens. If it still does not post, try the other stick of memory. If it still fails, you either have a bad cpu, mb or power supply, the video card rarely dies. See if you can find the burning smell. If anything is burnt, it would be the cpu, power supply or hard drive most likely.

 

[stucknok]

I did all the steps you suggested and still nothing happens when I hit the power switch. The cpu and motherboard look fine, no burnt spots or any smell that I can detect. Any suggestions on what to replace first? I realize the motherboard will be cheaper than a new cpu but don't want to waste money if the motherboard is ok. Any way to test the motherboard first? Thanks for your help.

 

[johnjkr1]

Without components to swap, there is no other way to test your mb/cpu/ps. I would go with the power supply first, they are the cheapest and die far more often than a cpu or a motherboard. You could also buy a super cheap old duron to test with, it would probably save you money in the long run.

 

[mechBgon]

I second the motion for a new power supply, and make it a high-quality brand like Enermax, Antec, or Sparkle Power/Fortron. No PowMax/Deer/CompUSA junk. If you want to buy for the future, get an Antec TruePower480 or 550 or an Enermax/etc. of similar caliber... I read that the upcoming high-end video cards will be drawing some fearsome amounts of power, to the extent that they'll require two four-pin auxiliary power cables to feed them. :Q

Even if the power supply isn't the only problem, a high-quality PSU just seems like a good idea for a computer that he relies upon.

Welcome to the Forums, by the way 🙂

 

[stucknok]

 

[stucknok]

Hey, everyone. I appreciate the info and suggestions. I now believe the mobo is the problem. I have tested the power supply and it is ok all though I do plan to upgrade to a better one. I can ground the power switch on pin on the ATX harness and I have power to all connectors(fans, drives, video card, etc.). I think the mobo is not seeing this state when the power button is pushed or else the board is damaged at this point of contact. Once again I thank you for your time and help.

 

[waitman]

again brand name power supply. I just went through this with my xp2500 system. sometimes it would boot up and the voltages appeared to be within specs, but I replaced it with an enermax and those problems disappeared.