Two computers both starting infrequently

GhostwriterMark

Honorable
Jul 30, 2013
7
0
10,510
Hi all.

I have two homebuilds which have been running fine for years, but suddenly both have started to misbehave. One froze and then failed to post for several days and I ended up replacing the motherboard, CPU, PSU and RAM, after which it seemed to run fine, then suddenly started refusing to turn on, restart or wake up from sleep at random. When starting from scratch it will one day work no problem and the next it will not post or beep. I've tried everything, but there are never any errors or any indication anything is wrong - nothing ever freezes prior to failing to wake up/restart.

The second homebuild has worked flawlessley throughout its many guises over the past 6 years, but now suddenly it too will sometimes not start - only this one will not even power on, let alone fail to post. I can post details on components tonight, but does anybody know why two computers might suddenly fail to start properly? Might the issue be connected?
 

GhostwriterMark

Honorable
Jul 30, 2013
7
0
10,510
Not for PC2, but PC1 (the real problem computer) has a brand new motherboard and therefore a new CMOS battery. Scratching my head over this one as it has refused to turn on and has actually turned on twice each since my post yesterday!
 

GhostwriterMark

Honorable
Jul 30, 2013
7
0
10,510
Left the CMOS battery out for about two hours but the machine still didn't start up. I've removed the computer now and hooked my laptop up instead - first time I've been beaten by a PC! At least I have some spares, even though one of them clearly doesn't work!

Thanks for your replies. If anybody comes across this thread and has any bright ideas though, please post as I'd gladly try and figure this one out and get it up and running.