Have to clear cmos before every boot

[Baldbloke]

Hi folks,

I have a very old pc which will be used simply for browsing. Alternatively I may just give it away to someone who has never had a pc before. It has a fault though. So I couldn't even give it away at this time.

It will not boot. No beep, no post, no bios screen. I clear the cmos. It boots and all is fine. It gets to windows XP. If I power down and switch back on within a couple of hours it boots fine. However, if left for a couple of days, it fails to boot as described.

It's an Asus A7N8X deluxe motherboard
AMD single core cpu (can't remember the model)
2 * 500mb ddr (Don't laugh)
80Gb sata hdd.

I have:

Removed all unnecessary hardware when testing for boot problem.
Replaced cmos battery for a known good one.
Tried both ram modules in all 4 slots 1 stick at a time.
Swapped the video card for a known good one.
Swapped psu for a known good one.
Flashed the bios to the latest firmware (when it did boot)
Set bios to failsafe option

I'm thinking the bios chip is the problem.

I should add that I used Nlite to modify my original XP disc in order to clean install XP on the sata drive. (Xp does not normally have sata drivers, hence the disc mod) But it doesn't get past the post when it does fail so I don't think that is part of the problem. Although, when it fails, I get no monitor output so I can't tell if it is detecting the hard drive , hasn't got that far, or what.

Anything I've missed?

Thanks for your help.

 

[Admiral Huddy]

Well you have done quite an extensive range of tests. My initial guess would have been to look at the PSU. The capacitors may be discharging when left for long periods of time but you said you've replaced this with a known working one.

Either something is discharging the PSU or as you said, it could be the BIOS or the VRMs.

I would see if you can get your hands on a cheap second hand motherboard.

 

[Baldbloke]

Thanks for the reply Admiral Huddy, the pc isn't worth spending anything on. I should really just scrap it. Then again, I can't let it beat me. Lol. Just for sheer stubborness I may buy a new/cheap/scrap motherboard and try it. Then, once it's working, and only then, I will scrap it.