PC not booting up occasionally.

[Hodsocks]

My second pc sometimes will not boot up, not even into post. It switches on, fans spin up, the hard drive light comes on and stays on as does the dvd writer light, although the dvd rom light goes off. I can reset, switch off and restart the machine and nothing more than the above.
Most of the time it happily boots up but just occasionally it behave as above. Tonight I had it on for about one hour, did some work on it copying some files across, switched it off for 30mins or so and now it wont boot.
I have checked and reseated all IDE cables, ram modules, video card, I have disconnected the dvd's and even the hard drive but still no success. I will probably turn it on tomorrow and it will be fine.
Occasionally it will boot into post and throw up an error message about it having failed to post several times and to hit F2 to enter BIOS or F1 to load defaults then it reboots and sometimes boots into windows and sometimes not.
I'm curious as to whats going on here, anyone with some suggestions?

 

[Rik]

It could be the psu is on the way out!!
It could be the mobo is on the way out!!
It could be the ram is on the way out!!
It could be the bios batter is nearly flat, replacing it may be a good idea!!

Get speedfan from the downloads section and use it to monitor things on it for a while!!!

Google and get memtest and use it to test the ram for atleast 8 passes!!!!

 

[Hodsocks]

Hi Rik, most of the parts in the pc are less than 6 months old so should be OK, not guaranteed of course. I have carried out memory checks and they were all OK, changed psu and still no improvement.
As I mentioned in my last post, I switched it on this morning and it booted straight into windows and I haven't touched it since last night,,.......curious.

 

[Rik]

Check the mobo very carefully for any domed or leaking capacitors!!! If you spot one and replace it now it could save further trouble!!!!