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I hope this is not an inappropriate forum.

I have a bootup problem that has me stumped. I have a desktop (Compaq Presario SR1750NX, AMD Athlon 64, Asus ABAE-LE motherboard, onboard ATI Radeon Express video, 3G RAM, 1.5TB + 500G disk) built in 2005. In the last 6 months or so, it has had 3 or 4 instances where, after power had been completely removed (plug pulled, not just shutdown), for >12 Hrs, the system would not come back up when it was powered up again. Lights would come on, fans would spin, but there was no other activity - absolutely no video, not even the pre-boot splash screen, no POST indication, even the soft power off didn't work.

When it was left powered on for several hours, it would suddenly boot and everything would be fine.

The first time it occurred, I replaced and upgraded the power supply, and still had the same results, so I don't think it's the PS.

It has occurred again following my upgrade last weekend to Win7 RTM. But this time, it's not coming back, even when left on for >24 Hrs.

When it first happened after the upgrade, I had been thinking maybe the CMOS battery had reached it's shelf life, so I replaced that. And it did come up a couple hours later. But then it went into a sleep state after being up for a while, and would not come back out of it. And it hasn't been backup since then.

Any ideas?

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migrated from Aug 14 '09 at 1:03

This question came from our site for system and network administrators.

This is better suited to - password is ewok.adventure to get in – Mark Henderson Aug 13 '09 at 22:05
The obligatory unhelpful IT person comment: "Weird, it's not supposed to do that..." – Jared Harley Aug 14 '09 at 1:22

I'm betting bad mobo, but very hard to be sure.

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Agreed, sounds like a very strange motherboard problem. Sadly, at this point, it's probably going to be a "replace component, test, next component, test, etc" until you find the problem. – Jared Harley Aug 14 '09 at 1:22
Well, since PS has already been replaced... mobo is next on the list. – derobert Aug 14 '09 at 6:58

Almost every time I have encountered this problem you describe - PC powers on but no display - it has been the motherboard. I have seen this so many times over the years that I can say this with some certainty.

Components on the motherboard such as capacitors, etc, can be replaced if you have a decent soldering iron, a steady hand and patience. Capacitors that are faulty usually bulge (rounded) on the top or are leaking through the top so they are easy to spot.

It would probably be easier to replace the motherboard but since it is a "name brand" PC it probably won't be cheap, especially if the PC will only accept their motherboard layout.

Hope this helps.

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Unplug everything except for the video card and one stick of memory see if that matters. If not, then pull that memory stick and replace it with the other one. Now try it in a different slot.

If you have another video card, try that too.

I would also pull the motherboard and set it on a cardboard box and see if it boots then.

It sounds very very much like the motherboard, but to be honest, after 18 yrs of doing this, I've seen it all, that's why I say try the above, it doesn't cost a thing.

If you pull the motherboard out and it still doesn't work, replace the mobo while you already have it out.

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I had this same issue with my old desktop computer. I found if it cooled off, it wouldn't boot. If I turned it on and let it warm up, then restarted, it eventually would come back.

My solution was to never turn it off until I replaced it.

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Seems like a hair-line crack on the motherboard. When the computer heats up the crack is getting closed and the fault disappears.

My laptop mobo has this, affecting one memory bank. When I only use one there is no error. When I want to put RAM into the other one I have to do it with a warm laptop.

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Two quick questions/ideas:

  1. What to the capacitors look like on the motherboard? Use a magnifying glass with light if you can. Pay special attention to the electrolytic cans. Could these capacitors have failed? See Wikipedia article on Capacitor plague.

  2. During AC power cycle, is your clock accuracy affected? Does the computer keep good time when the AC is powered off? Maybe the RTC watch crystal is bad.

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