PC shuts down right after OS boot

My PC keeps shutting down right after Windows(7) boots up. Sometimes it happens within 15 seconds, other times I get a couple of minutes before it dies.

I ran tests on the hardware at a friend's place, and the RAM, GPU, and CPU all passed. They're fine.


Initially, I suspected the motherboard or the hard drive. Since I had a spare drive lying around, I swapped out the old one—which was riddled with bad sectors anyway. We did a clean install of Windows, loaded the drivers and all the necessary software, and everything worked perfectly on his machine.
But the second I brought it back home, the same problem returned. It shuts down post-boot, sometimes sooner, sometimes later.

The only variable is that we used a different power cable at his house.

Athlon 3200 2.2 GHz
DDR 1.5 GB
HD 2400 Pro
HD 80 GB

Kevin Kim7 said:My PC keeps shutting down right after Windows(7) boots up. Sometimes it happens within 15 seconds, other times I get a couple of minutes before it dies.

I ran tests on the hardware at a friend's place, and the RAM, GPU, and CPU all passed. They're fine.


Initially, I suspected the motherboard or the hard drive. Since I had a spare drive lying around, I swapped out the old one—which was riddled with bad sectors anyway. We did a clean install of Windows, loaded the drivers and all the necessary software, and everything worked perfectly on his machine.
But the second I brought it back home, the same problem returned. It shuts down post-boot, sometimes sooner, sometimes later.

The only variable is that we used a different power cable at his house.

Athlon 3200 2.2 GHz
DDR 1.5 GB
HD 2400 Pro
HD 80 GB

You've covered almost everything, but you missed the most obvious culprit... the power supply unit. 😵😵😵

There isn't really a solid way to test out a power supply unless you just swap it with a buddy's and see if things stabilize... Might be your CPU overheating though? Maybe the system is just shutting down to save itself from frying...

The power supply issue is evident once you look at that "negative voltage" table. You aren't seeing the expected -12V or -5V readings; instead, it’s just some negligible nonsense. However, it remains unclear how exactly you went about testing this.

I wouldn't really trust those programs when it comes to voltage readings...

Hardly... I wouldn't go that far. We need something capable of displaying at least the third decimal place...
One has to admit, the discrepancy is massive; there isn't even a hint of a "negative" voltage swing.
It is quite simple: just verify the readings with a multimeter that costs roughly $17. The power supply is always the critical failure point. Looking at the data table, it is patently obvious that things are not right.
Admittedly, checking the BIOS is an option, which would be considerably more straightforward.

Sensors can be incredibly finicky—they’ll give you readings that just don't make any sense sometimes. Plus, since every motherboard layout is a little different, the sensor placement varies so much that the software might pull data from the wrong spot or even accidentally aggregate multiple sensors into one messy number. Don't get me wrong, HWMonitor is perfectly fine for a quick bit of basic troubleshooting, but I wouldn't bet the house on those specific numbers being 100% accurate.
That said, I'm right there with you on checking the power supply. Honestly, the best move is to see if you can borrow a different unit just to rule it out completely.

This power supply is ancient, and honestly, it’s one of those cheap, off-brand pieces of junk you see everywhere. 😁 I figured I could just toss it out of the equation since a PSU should either work or it shouldn't—it shouldn't be acting up by crashing after an hour one time and then a single minute the next.
I went ahead and grabbed a replacement, and now the rig is actually running.

p.s. Can someone break down how power supply voltages work? Specifically, how can I tell if the readings are off and something is failing?

Man, I really wish I could just grab a multimeter and start testing all those rails... you know, the +12V, +5V, and +3.3V ones...

Like, check the voltage while the PC is just idling versus when you're absolutely redlining it with some heavy software, just to see if the levels are holding steady or jumping all over the place.

Jonathan Mendoza17 said:Sensors can be incredibly finicky—they’ll give you readings that just don't make any sense sometimes. Plus, since every motherboard layout is a little different, the sensor placement varies so much that the software might pull data from the wrong spot or even accidentally aggregate multiple sensors into one messy number. Don't get me wrong, HWMonitor is perfectly fine for a quick bit of basic troubleshooting, but I wouldn't bet the house on those specific numbers being 100% accurate.
That said, I'm right there with you on checking the power supply. Honestly, the best move is to see if you can borrow a different unit just to rule it out completely.

🙂

Regarding the power supply, you aren't relying on some arbitrary sensor; measurements are taken directly via an A/D converter, and that single component handles all voltage readings. In my experience, instability in the power supply is the most frequent culprit behind sudden system freezes or hard shutdowns.
I must reiterate: the data in the table looks perfectly fine on paper.
Additionally, you can verify the voltage levels within the BIOS itself, provided the system stays stable long enough to check.

Kevin Kim7 said:This power supply is ancient, and honestly, it’s one of those cheap, off-brand pieces of junk you see everywhere. 😁 I figured I could just toss it out of the equation since a PSU should either work or it shouldn't—it shouldn't be acting up by crashing after an hour one time and then a single minute the next.
I went ahead and grabbed a replacement, and now the rig is actually running.

p.s. Can someone break down how power supply voltages work? Specifically, how can I tell if the readings are off and something is failing?

Voltages are permitted to fluctuate by a few percentage points, depending on the health of the unit and the current system load. You can check the levels in the motherboard BIOS during startup. For real-time monitoring, you could purchase specialized adapters to plug into the connectors, though there is little need to obsess over such things. If you suspect the PSU is failing, simply disconnect a CD/DVD drive or any non-essential expansion card; if the shutdowns cease, the conclusion is self-evident.
It is much like when a car battery starts to lose its charge...

Thanks to everyone for the advice 🙂