PC emits very loud “pop” noise four times over a span of 5 months yet everything is working fine. Suddenly, without warning, the computer shuts off completely. Upon reboot, the system barely passes POST (Power On Self Test, or BIOS (Basic Input Output System)) without shutting off again. I receive a frantic phone call. “What’s wrong? Why doesn’t the computer turn on anymore? I didn’t do anything!”

System Background:

This is a system that I built for a law firm, no fancy components were necessary except for the RAID 1 for backup in the event of a hard drive failure.Most of the components were new and in excellent condition.

System Specifications:

AMD Athlon X2 4800+ (Socket 939)

ASUS A8V-XE Mainboard

Antec Earthwatts 650w PSU

4GB DDR 400 PC3200 Corsair Memory

3x SATA HDD (2 of which are in a RAID 1)

2x DVD/RW

Linksys Wireless PCI Card

EVGA NVIDIA GeForce 7300 GT (AGP) 256MB

Diagnosis:

My initial thought is that perhaps too much dust has built up in the machine until finally it is simply overheating and cannot handle it anymore. A long shot, but the best diagnosis I could make over the phone. I also suspect the PSU (Power Supply Unit) has failed or that perhaps the system has suffered from a massive surge because the house in which it resides is rather old. I request that the system be brought to me for further inspection.

I opened the PC case and did a thorough cleaning to make sure that no dust was building up strong enough to create any intense heat. I blasted out a fair amount of dust, but didn’t observe enough dust to overheat the whole system. I then proceeded to plug in the unit to run a test power-on. When I hit the front power button, the PSU fan kicked in, CPU fan started up — and then all power was immediately cut off from the system without warning. Tried again, same thing.

I shined around with my flashlight to check for motherboard grounding issues, which seemed unlikely since I made the system myself and was careful to secure the motherboard — and the fact that the system had been running solid, never turned off, for over a year and a half. No motherboard grounding issues. I then unplugged the main power from the motherboard and plugged it into my trusty power supply tester. To my surprise, everything was fine, all lights were green and all fans were humming along perfectly. So now I could rule out the PSU as a potential problem.

At a loss for other options, I began unplugging everything, DVD/RW drives, HDDs, the video card and the PCI wireless adapter.

Now the system powered on and stayed powered on. So, what’s the cause?

Cause:

Four blown capacitors on the video card.

Capacitor Resources:

Badcaps

How Capacitors Work

PCs Plagued by Bad Capacitors (article)

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