[SOLVED] Long time PC now 'stops' everything after some seconds on, but there is still energy [intermittent]

Oct 9, 2020
I have here an old family PC that's now showing an intermittent problem. The PC was working well all of these years, and nothing different was done to it recently (no hardware upgrade/maintenance).

The specs:

MB: Gigabyte GA-G31M-ES2L
CPU: Intel Pentium 4 3,20Ghz
RAM: 2 Kingston KVR 2 GB (total 4 GB RAM)
GPU: Onboard
PSU: VCOM ATX 400W - HCHEC-400T -> I think it's more fair to say this is an unbranded/generic PSU, very common here in Brazil
HD: Western Digital 80Gb SATA (WD800JD)
SO: Windows 7 Home Premium 64bit
Case: Unbranded

The Problem:

There are some variations of the problem:

1) The most common: when I turn the PC on, the PC works for some seconds, sometimes a minute or so, and then it simply stops everything, but without losing the energy. I lose video (monitor shows a black screen), the keyboard stops responding (leds indicator doesn't switch on/off), and the hard drive led indicator of the case stops blinking. However, the PC is still energized; the CPU fan is still spinning/working and that typical sound of PC on is there. When I reach that point the only thing left for me to do is hold the power button of the case for 5 seconds to turn it off.

So just to make it clear: when I turn the PC on, in these seconds that it's working I have video, the keyboard works, the HD led blinks, and the PC makes that standard 'beep' sound. And I didn't find any pattern; sometimes this 'blackout' occurs when Windows is initializing, sometimes occurs when Windows already started, sometimes it occurs during post screen. Even when I enter the bios setup the system blackouts after some seconds.

2) Second variation: sometimes I can't even start the PC. When I press the power button, the PC energizes, the CPU fan spins and that typical sound of PC on is there. But nothing more happens. No video, no beep, no HD led indicator, no keyboard, nothing. When that happens, not even the power button of the case works, and I have to tun the PC off by disconnecting the power cable in the back. (An interesting note here: for two times when the PC reach this state and I can't think in nothing more, I just let the PC on in that state, and for my surprise the system started after about 10 or 15 minutes. But this just happened twice. In other cases I have already left the PC on in this state for hours and nothing happened).

3) Third variation: as I said before, the problem is intermittent. There are times when the PC works just fine, the Windows starts normally and we can work on it as before. When that happens, sometimes the PC works for hours, and sometimes it works for a few days. There was a few cases where the PC worked for a few weeks. Until the day it stops again and all that cycle starts once more. When the PC starts with its problems, sometimes that blackout occurs when we're working on PC, but in general the problem starts all over again in any given day when I try to turn it on the next day.

Things I've already tried:

  • Clear the motherboard CMOS (removed the battery, waited 5 minutes)
  • changed the battery
  • removed all the peripherals, leaving just the motherboard, CPU and PSU
  • changed memory from slots, tested each one individually
  • disconnected all the wires of the case from the motherboard
  • cleaned the PC
So I'm convinced it's a hardware thing, but I don't know how to solve it. I'm in home and don't have other peripherals to test. Hope to find some solution from you guys.

Last edited:
Oct 9, 2020
I don't have another PSU to test, so if is this I'll have to take it to repair.

What are the chances of being the CPU temperature? Does that make sense?
Oct 9, 2020
Old & poor-quality PSU has to be the prime suspect in my book.
It worked! It was the PSU.

I managed to get another PSU from somewhere else, and tested for an entire week. The PC is now working flawless, no sign of problems. So I'm convinced it was indeed the PSU.

Thank you very much for your help friend! Well this topic is over for me, but I don't know how to mark it as 'Solved' (this is my first thread here in this forum).

Before we go, I'd like to ask if it's too difficult to fix a PSU myself. I have no knowledge in electronics.

Phillip Corcoran

Internal PSU faults cannot be fixed -- best policy is to replace it. It's dangerous to open up PSU anyway.

In any event, if a PSU is old & poor quality, it will always be old & poor quality.

To mark this thread as "Solved", please click the trophy icon on the left-side of my first post. That will mark the thread as solved as well as earning me a few brownie points 🙂