PC turns off randomly, mid boot or after running for hours.

[Frosty11]

Configuration:

Processor- Intel Dual Core E5700

GPU- Internal

Cooler- Stock Intel LGA775

RAM- 2GB Kingston 1333MHz / 2GB EVM Dynet 1333MHz

Mobo- Gigabyte GA G41M Combo

HDD- Seagate Barracuda 500GB

PSU- 400 W Circle Power Supply

Case: Some generic no brand case

OS- Windows 8.1 64 Bit

 

Have run with this config (except the new PSU) for a couple years without issues. For the past one month my PC has been randomly turning off without warning or BSOD. Sometimes while booting and after running for hours at other times.

 

What I have tried so far:

1. Replaced the old PSU with leaked capacitors with a new one.

2. Replaced dead CMOS battery.

3. Cleaned the heatsink and re-installed it with new thermal paste. (Temps normal now while idle ~40 deg c and under load ~72 deg c)

4. Reseated the Processor.

5. Tried one RAM stick at a time and both.

6. Checked the PSU voltages. Fan runs normally with Green and Black pins shorted. Here are the readings: All Orange Pins: 3.39v, All Red Pins: 5.37v, All Yellow Pins: 12.19v, Gray (Pin 8): 5.35v, Purple (Pin 9): 5.25v, Blue (Pin 14): -11.62. The Red pin voltages have me a little worried because according to this article the max voltage for Red pins is 5.25v.

7. Tried breadboarding. PC ran fine for few hours but it runs fine for a few hours in the case as well. So I think breadboarding was inconclusive.

 

The BIOS speaker beeps once while booting which indicates all is fine with my Award BIOS. One of my mobo standoffs is missing but I put a cardboard between the mobo and case, so I don’t think the mobo is shorting on the back. Also cleaned the mobo as much as I could. I have no overclocks or under volting. There seem to be no loose screws lying around. All cables are plugged in properly. Another thing worth noting is that once it turns off, pressing the power button on the case won’t start the PC. I have to unplug the PC from the wall socket and plug it back in before it can turn on.

 

Someone help me out here. If more info is needed I'll add it.

[MrDrWho13]

I would still look at the PSU as being the fault. Is "400 W Circle Power Supply" the new one? You might want to try a higher quality one.

[Shocktruppen]

I would try using cupid hwmonitor to see if you an observe a problem with power or temp problems before the pc turns itself off.https://www.cpuid.com/softwares/hwmonitor.html

[Frosty11]

3 hours ago, MrDrWho13 said:

I would still look at the PSU as being the fault. Is "400 W Circle Power Supply" the new one? You might want to try a higher quality one.

I was hoping its not the PSU, its new after all. Maybe I should send it for repairs, its under warranty.

[Frosty11]

2 hours ago, Shocktruppen said:

I would try using cupid hwmonitor to see if you an observe a problem with power or temp problems before the pc turns itself off.https://www.cpuid.com/softwares/hwmonitor.html

I did use HWMonitor. All temps looked normal.

[Shocktruppen]

6 minutes ago, Frosty11 said:

I did use HWMonitor. All temps looked normal.

How about the power? Anything look low or high or fluctuating?

[Frosty11]

1 minute ago, Shocktruppen said:

How about the power? Anything look low or high or fluctuating?

Power as in the voltages right? Nope I didn't look at the voltages. What should I be looking for exactly?

[Shocktruppen]

At the top of hwmonitor it shows voltages. I would look for anything way low or way high than what the base shows like 5v , 3.3v, and especially 12v. THE vin 3 and vin4 should read the same as your bios presets, along with your vcore.

[Frosty11]

24 minutes ago, Shocktruppen said:

At the top of hwmonitor it shows voltages. I would look for anything way low or way high than what the base shows like 5v , 3.3v, and especially 12v. THE vin 3 and vin4 should read the same as your bios presets, along with your vcore.

I see. I'll check for these and update you. How do I find the base voltages. Afaik HWMonitor just displays the Current Value, Min and Max value.