PC won't power up

Lou[NE] · Post by **Lou[NE]** » 30 Dec 2006 8:43 am

Son's PC just up and shut itself off and won't power up again. Power button seems functional (ohmmeter shows no resistance when switch is pushed in, infinite resistance when not); power supply seems OK (works in another PC); a different good power supply in son's PC will not power up. Looks like something is not getting a signal telling it to power up. Wha' happened?

Thanks in advance.

Lou

winston · Post by **winston** » 30 Dec 2006 8:55 am

Sounds like a bad motherboard to me. winston may

Wiz Feinberg · Post by **Wiz Feinberg** » 30 Dec 2006 12:34 pm

Open the case and carefully examine all of the electrolytic capacitors for bulging and leakage. This was a common cause of motherboard failure in boards manufactured in Taiwan and Singapore, a couple of years ago.

Also, examine the heatsink and fan on the CPU for looseness of the heatsink on the CPU, or seizing of the fan. Both will cause shutdows from thermal runaway.

Lou[NE] · Post by **Lou[NE]** » 30 Dec 2006 4:29 pm

No bulging caps that I can see; cpu cooler is seated firmly and the fan runs when plugged in to another motherboard.

Methinks I'll be looking at a mobo/cpu bundle unless anyone has any cheaper ideas.

Thanks to all.

Lou

winston · Post by **winston** » 30 Dec 2006 9:16 pm

You probably won't need a processor, just a mother board, unless you just want to upgrade.

Dave Potter · Post by **Dave Potter** » 31 Dec 2006 6:45 am

One last long shot before you pull the mobo.

If the PC power switch has been left "On", and on/off functions have been controlled with the front panel button, try switching off the back panel switch for a few minutes, then back on, and press the front panel button. I've found Windows power management a little quirky on occasion.

I'd also try experimenting with the power management options in the bios, as well, before going to the trouble of replacing the mobo.

Wiz Feinberg · Post by **Wiz Feinberg** » 31 Dec 2006 11:37 am

Unplugging all cables and power plugs from a computer will sometimes allow it to reset itself, after a power event caused a bad shutdown.

Check the DC power connector where it clamps onto a socket on the mobo, to be sure it is firmly seated.

Other things that can disable a mobo from booting are a fried hard drive, or bad plug-in card, or short circuit caused by a piece of metal falling onto exposed terminals or IC leads.

Lou[NE] · Post by **Lou[NE]** » 31 Dec 2006 3:28 pm

Dave, tried the power supply switch reset trick, no joy. Can't mess with bios setting if the mobo won't power up.

Wiz, everything on the mobo seems solid, and I have unplugged-replugged all connections. The hard drive shows up as healthy when connected as slave on another PC.

I'm considering the mobo/cpu bundle because a) the deadster is a Socket A, which I believe is close to obsolete, and b) with no way to power the mobo, how do I know the cpu isn't fried? I don't want to wind up with a new mobo and a dead cpu.

Thanks again to all, and best wishes for a prosperous and peaceful 2007.

Dave Potter · Post by **Dave Potter** » 31 Dec 2006 4:44 pm

Lou[NE] wrote:Dave, Can't mess with bios setting if the mobo won't power up.

Of course, you're correct, Lou. Sorry, wasn't thinking.

Jon Moen · Post by **Jon Moen** » 31 Dec 2006 5:33 pm

Is it possible that the bios battery is dead"? Although, the computer should still do something even with a dead battery.

winston · Post by **winston** » 31 Dec 2006 5:38 pm

I would not think the processor is fried unless its been hit by lightning. My vote is motherboard.

Lou[NE] · Post by **Lou[NE]** » 6 Jan 2007 2:44 pm

I didn't like the looks of the Socket A motherboards I looked at, so I bit the bullet and bought a mobo/cpu bundle - Biostar NF4 4X-A7 with Athlon 64 3000+ cpu. Son is happy - says the new rig is faster and quieter than the old. Problem is resolved; thanks to all who responded.

Lou