PC shuts down under load

[cglaeser 0]

I have an aging PC that shuts down abruptly when some programs are run, and sometimes on start-up. It seems to run fine for hours in Safe Mode under modest load. There are no apparent entries in the Event Log. The power will just suddenly turn off.

 

What is the most likely cause? A faulty power supply?

 

Best,

Christopher

[Birdman Adam 0]

My best and most probable guess is that the over-current protection on the PSU is cutting power to prevent damage to the PSU. Solution is to get a larger-capacity PSU. If you have a multimeter/kill-a-watt, use it to see how many watts the PSU draws from the wall. If its within like 80+% of the PSU rating, then your working the PSU too hard.

 

So say you have a 250W PSU drawing 220W with the computer under a moderate load. That PSU won't let it draw much over 250W before its going to shut down. Another test you can do is use a multimeter to watch the voltages of the rails (12V, 5V, 3.3V, etc). Watch and see as they dip down some once you work the computer hard!

 

I actually have an old Dell P4 machine in which I can hear the fan slowing down when the CPU is at 90+% load!

[cglaeser 0]

Thanks for the quick response. I do have a Watts Up Pro and will try that. This PC has been working in this configuration for almost five years without any power failures, so perhaps the tolerances have drifted with age. It also got pretty warm in the computer room this week, so perhaps that caused some damage as well.

 

Best,

Christopher

[ak357 0]

My best and most probable guess is that the over-current protection on the PSU is cutting power to prevent damage to the PSU. Solution is to get a larger-capacity PSU. If you have a multimeter/kill-a-watt, use it to see how many watts the PSU draws from the wall. If its within like 80+% of the PSU rating, then your working the PSU too hard.

 

So say you have a 250W PSU drawing 220W with the computer under a moderate load. That PSU won't let it draw much over 250W before its going to shut down. Another test you can do is use a multimeter to watch the voltages of the rails (12V, 5V, 3.3V, etc). Watch and see as they dip down some once you work the computer hard!

 

I actually have an old Dell P4 machine in which I can hear the fan slowing down when the CPU is at 90+% load!

 

Old means dust

Dust means check all computer fans and MB

overheat ?

[cglaeser 0]

Old means dust

Dust means check all computer fans and MB

overheat ?

 

Good suggestion. I thoroughly cleaned it last night, but perhaps the heat has already caused some damage. It sill shuts down when loaded.

 

Best,

Christopher

[Birdman Adam 0]

Even with the other PSU you have?

[ak357 0]

Good suggestion. I thoroughly cleaned it last night, but perhaps the heat has already caused some damage. It sill shuts down when loaded.

Best,

Christopher

 

If u can check and change MB capacitors

[Soundy 1]

Good suggestion. I thoroughly cleaned it last night, but perhaps the heat has already caused some damage. It sill shuts down when loaded.

Best,

Christopher

 

If u can check and change MB capacitors

http://en.wikipedia.org/wiki/Capacitor_plague

 

Note: this sort of damage is not generally heat-related, it's just a result of bad caps.

[Campbell 0]

Good suggestion. I thoroughly cleaned it last night, but perhaps the heat has already caused some damage. It sill shuts down when loaded.

Best,

Christopher

 

If u can check and change MB capacitors

 

Love this place!

 

Standard answer elsewhere. Purchase new product

Standard answer here. Get your hands dirty and fix the electronics yourself!

[cglaeser 0]

Even with the other PSU you have?

 

I have not replaced the PSU yet. I'm still using the original 600W PSU.

 

Best,

Christopher

[rory 0]

Power Shuts off?

Bad power supply/capacitors

 

1-Change PSU

2-Change MOBO

 

Other issues can cause it but PSU is the most common - in my experience as a PC tech in a 3rd world country with terrible electricity, PSU is the most common cause. I replace them several times a year, rarely ever any other hardware - hard drive is 2nd on the list for replacements. AVR normally prevents HDD from failing but PSU's seem to fail either way, ofcourse more so without an AVR.

 

BTW, I wouldnt dream of plugging in a computer or DVR without an AVR, if you have one in this case then its likely just a poor PSU (Ive had brand new PSUs die 5 minutes after plugging them in, even $100 Antec PSUs) or extra heavy brownout (Ive had clients with AVRs and UPS that caught fire, even APC), if not on some kind of AVR then its expected - regular surge protectors are typically useless for anything other than basic surges.

[Birdman Adam 0]

BTW I can vouch for the 'capacitor-plague'. I have probably saved over $1000 in monitors that would not power up, simply because cheap caps failed, and the PSU output was too rippled.

[cglaeser 0]

If the PC is booted in safe mode, it will remain powered up. The graphics card is an nVidia FX 4500. According to the specs, the power requirements are 109W. Although the problem is likely a faulty PSU, I'm guessing the PC may stay up if I replace the FX 4500 with a low power graphics card.

 

Best,

Christopher

[skane 0]

Check the mobo caps for bulging before deciding to dump any more money into the PC. I've seen lots of PCs die with bad caps; random BSODs and shutdowns under load are symptoms.

 

If the caps look good, blow out the dust, and monitor temps.

 

If still having probs, swap in a known good PSU.

[Soundy 1]

Check the mobo caps for bulging before deciding to dump any more money into the PC. I've seen lots of PCs die with bad caps; random BSODs and shutdowns under load are symptoms.

QFT: bad caps are very easy to see in a visual check. These days, this is the first thing I look at for just about any issues that seem hardware-related, because it's quick and easy to either confirm or rule out.

[cglaeser 0]

I don't see any bad caps, but I'll go back and check each one very closely with a penlight. I connected the Watts Up Pro and it hovers around 290W with a peak of 313W in Safe Mode. When I try to boot in normal Windows mode, the power gets to 445W and shuts down. If I get time tomorrow, I'll purchase a new PSU and see if that resolves the problem.

 

Best,

Christopher

[Soundy 1]

I've seen PSUs develop bad caps as well... we had a run of about a dozen Vigils that came with "Sparkle" brand PSUs, all of which died within about 2 months of each other. Replaced them with new Antecs under warranty Dunno if that was caps or something else (I haven't actually taken one apart to look at it), but that particular brand of PSUs turned out to be very flaky. If memory serves, most of them were 550W-650W, too.

[Birdman Adam 0]

So the computer is shutting down when it pulls 480W from a 600W PSU? Sounds like a crappy PSU.

 

A thing I should point out is on most mobos today, the electrolytic caps are those stronger 'solid-state' ones. I think these are working better these days...

 

BUT in PSUs, they are still using the old electrolytics with the brown, ,blue, or black wraps and pressure-releases on top. Plus these are submitted to more heat. If there is no warranty on the PSU in question, I'd open up the PSU in question and have a look around!

[mike_va 0]

I don't see any bad caps, but I'll go back and check each one very closely with a penlight. I connected the Watts Up Pro and it hovers around 290W with a peak of 313W in Safe Mode. When I try to boot in normal Windows mode, the power gets to 445W and shuts down. If I get time tomorrow, I'll purchase a new PSU and see if that resolves the problem.

I had a HP that worked for years then started doing that. Turns out as I had added video card, hard drive etc I started to tax the supply and eventually put it on the edge of failure.

 

I say edge since I could bring it up on a variac and get it to stay powered...then one day swapped the supply when this no longer worked. Could not even find a supply as small as what they had put in there...ended up cutting out a little metal work in the chassis to get it to fit. Never occurred to me they had all these expansion bays etc but had not included a power supply that could power the items one might add...