Why will the computer turn off (interesting)?

Question

Iron

Good afternoon.
There is a PC
Power supply: Logic Power Pentium P4 ATX-420w Motherboard
: Asus M2n68 Plus
Processor: amd athlon ii x4 630 2.8ghz
RAM: Goodram DDR2 2GB PC2-6400 Dimm + Goodram 2GB PC2 6400Dimm
Video: Geforce GT9500 1Gb
Screw: Toshiba 500Gb on 7200 rpm
The PC turns off almost immediately after pressing the power button ..
Sometimes it works for a while and turns off ..
It was like that for 2 weeks it did not turn off and started to turn off again.
Changed thermal paste, no overheating.
If you remove the RAM from the PC (all), then the PC turns on and the cooler spins. But not long ago I bought a second bar of RAM and it was obviously working, and the computer with only the new RAM inserted was also turned off.
Where to dig, what could it be? How to find out the problem..

Answer 1

Perhaps the PSU is old and "exhausted" and it does not have enough power. And / or swollen capacitors on the motherboard / PSU. It's easy to check - see if the capacitors are swollen and replace the PSU with a new and known to be good one.

Answer 2

Memtest RAM, HDD hard test for bad blocks, checking loops. Also try resetting the bios battery.

Answer 3

It was similar - not a new computer periodically turned off. It turned out - in the PSU false soldering. Soldered all the legs on the board - the problem is gone.
Borrow a PSU for testing. Helped - repair or change your PSU. Did not help - most likely, the motherboard.

Answer 4

Check carefully whether everything is connected correctly and whether there is a short circuit somewhere. Check power supply. It’s also worth trying to play around with the memory sticks: first check one in all slots, then the second one in the same way. Or the problem is with the motherboard itself.

Answer 5

The problem was in the power supply .. What does it have to do with the line going to the processor.
If you do not connect the processor power, the unit worked. (It doesn't work anyway..)
I'll try to fix it somehow.. And now the computer is working successfully with a new 650W power supply.