Need solution : Is it the Motherboard or SMPS or both ?

[Winter]

Is it the Motherboard or SMPS or both ?

I've got an old PC lying around with the following configuration -

P4 2.4 Ghz Socket 478
RAM - Hynix 256mb DDR
Mercury KOB845GL NDMx v1.2 Onboard Intel 845GL Graphics Chipset/CMI9738 Audio
SMPS - 300 Watts LPT2
Samsung 40 GB HDD SP0411N 7200 RPM
Sony DVD Rom DDU 1622
Realtek 8139/810x Family Fast Ethernet NIC
Samsung PS/2 SDM 4500 P KBD
Logitech M-UV96 Optical USB Mouse
Samsung SyncMaster 753S 17"

OS - Windows XP Dark Edition V.3

SYMPTOMS -

1. - PC shuts down randomly and once it shuts down it will not boot up instantly.On restart I only see the Power LED glowing, HDD LED is off and there's no beep or display.But it does boot up normally if I start it after a couple of hours.

2. - On rare occasions,only the display goes off but I can see the HDD & power LED glowing.

3. - I cannot add two RAMs or attach a second ROM/Writer anymore.When I add an extra memory module it either gives irregular beep codes + corrupt display or no beep at all + no display.In case it boots up the system perfomance is really bad and system crashes sometimes.On adding a 2 devices on IDE 2, the slave refuses to even read a normal CD and the master reads very slow.Did not boot on two instances.Both RAMS used to work in both slots earlier and the pair of IDE 2 devices as well.

WHAT I HAVE TRIED -

1. - Decompiled and Cleaned the system.
2. - Switched OS
3. - Cleared CMOS and changed every possible BIOS setting
4. - Flashed the BIOS
5. - Stripped down the system to Mbd,Processor,RAM only during Symptom 1 and there was no beep/display on removing the memory module either.
9. - Ran diagnostics on the system from a boot CD and all devices passed.

The only thing that's left is to borrow an SMPS from a friend which is difficult or take the entire tower to his place and check but I've kept that as the last resort.Has anyone encountered this kind of a problem ? Is it the SMPS or the mainboard or both ?

[unidentified]

Well, If you onle had a second PSU then you would have checked whether it is just a normal PSU problem or the motherboard. How old is this rig, if in warranty then try changing the motherboard.

[Howerski]

Hi,
which OS you were using previously and to which OS you have switched to.

Have you properly formatted your Computer.

Regards,

[Winter]

@unidentified
The mobo and SMPS was bought way back in 2003.I did try to get in touch with Mercury but I think they have shut down.Their website was last updated in 2005.

@Howerski
Yup.I format the computer completely atleast twice a year.Windows Server 2003 and Windows 2000 Pro were used earlier with the original configuration.But that was for a year or two.After that it was Windows XP + different Service Packs/Modded versions.Funny thing is that I installed Windows Server 2003 again and it gives the same issue.

[Winter]

I forgot to mention another issue which just took place and I managed to get the system running after like 4 tries.The hard drive is not detected sometimes.Says - Boot failure.Attach hardware blah blah blah.