Is your desktop computer running slower than usual? Does it randomly or frequently freeze up or restart? Or maybe it doesn't boot to the operating system or even boot at all. If so, your computer could have a failed capacitor.

Every computer repair shop has its own set of standard procedures, and we are no different. The very first thing we do when someone brings in a desktop computer is check for blown capacitors. With a quick visual inspection, we can spot a costly computer repair. And you can too. Here's how to inspect your desktop computer for failed capacitors.

Symptoms of bad capacitors

Now before you go and take your system apart, let's take a look at the symptoms of a failed capacitor. Does your computer have any of the following problems?

• Runs slow
• Randomly freezes up
• Randomly / constantly restarts
• Won't boot to an operating system
• Won't start at all

If so, it might be worth the time to take a look inside your computer.

Types of capacitors

Visual differences between water-based and polymer-based electrolyte capacitors

There are primarily two types of capacitors used on computer circuit boards (motherboards, graphics cards, etc.), water-based electrolyte and polymer-based electrolyte. I have seen the majority of failures with water-based capacitors, but polymer-based do fail too, just not as often. From 1999 thru 2007, millions of faulty water-based capacitors were produced by some Taiwanese manufacturers. The electrolyte will evaporate and turn into a gas, thus bulging the case and leaking in some cases.

Checking for bad capacitors

Top view of a row of failed capacitors

Side view of a failed capacitor

The following can be performed with the computer in-place, provided you have enough room. If not, you will have to move your computer to a location that does. Please take a photo of where everything goes first and completely disconnect all cables attached to it.

1. Power down your computer and
• Remove the power cord from the back of the power supply (in-place inspection)
  or
• Disconnect all cables (relocated inspection)
2. Open the case.
3. Remove any obstructions, like fan shrouds, so that you can view the entire motherboard and other add-in cards.
4. Using a flashlight, visually inspect all capacitors on the circuit boards (motherboard, graphics card, etc.). You may need to remove some of the add-in cards to examine them physically. Visual symptoms include:
   • Bulging or cracking of the vent on top
   • Casing sitting crooked on board as the base may be pushed out
   • Electrolyte that may have leaked out on to motherboard (rust-colored)
   • Case is detached or missing

What to do if you find a bad capacitor

If you do find a bad capacitor, there are three (3) options. First thing, if your computer is still operable, backup your data ASAP (see links below). There are many factors involved in deciding which option to choose, the system's age, and cost being the two major ones.

1. Repair the motherboard
   You can replace the bad capacitor yourself (see link below) or have a trained professional do it for you.
2. Replace the motherboard
   eBay is a great place to find a refurbished motherboard.
3. Replace the computer
   If you've been looking for an excuse to get a new computer, you just found one. Or maybe two or three.

For more information on failed capacitors:

Capacitor plague - Wikipedia

For more information on how to replace failed capacitors:

Recapping your motherboard - Badcaps.net

For more information on how to backup your computer:

Windows XP Backup

Windows Vista / Windows 7 Backup

Windows 8 Backup

Windows 10 Backup

When it comes to computer repair, you have to be a detective of sorts. And once in a while, I come across a really good mystery. I recently got an HP M7360N in the shop that would randomly freeze-up in Windows XP when you moved the mouse. It would run perfectly fine in Safe Mode. Maybe a bad driver?

A check of the event logs yields absolutely nothing, not a single error. I check Device Manager and find the hard drive controller listed under the Unknown category, even though it is correctly identified as an Intel controller. I uninstall it inside Device Manager and then scan for hardware changes. The hard drive controller reinstalls back into the Unknown category.

The system is still freezing up randomly when the mouse is moved. I tried a PS2 and USB mouse and got the same results with both. I disable all non-essential drivers and reboot with no change. I download the original and latest drivers for the system, trying all with no luck. Maybe a corrupt installation?

I create an image of the hard drive and then wipe it clean. Using the supplied recovery disks, I proceed to re-install the operating system and recovery partition. The system froze-up three times during reinstallation. But this time, the hard drive controller is under the correct category, IDE ATA/ATAPI controllers. It's starting to look like a hardware issue.

I run a few DOS-based utilities to test the memory, hard drive, etc. with no luck. I even try the HP recovery diagnostics. Every test I run tells me that there is nothing wrong with the hardware. Using the keyboard only in Windows, I can install another utility to test all of the motherboard components. I allow it to run for six hours, and the system passes every test.

The BIOS is the next place I look and find it's a few versions older than what is currently available for download. I download and install the latest BIOS version, and it still keeps freezing up randomly when the mouse is moved. I start searching the internet for clues.

After a few different search queries, I come across an article at Badcaps.net discussing symptoms of capacitor failure on motherboards, one being 'system randomly and frequently freezes'. I check the motherboard thoroughly and find no capacitors that look bad. I start checking the expansion (add-in) cards, and all at once, the mystery was solved.

There on the graphics card was a bank of capacitors that the tops were swollen.

Top view of the graphics card showing the difference between good and bad capacitors.

Side view of the graphics card showing the difference between a good and a bad capacitor.

The movement of the mouse on the screen was causing the graphics card to freeze-up. I re-assembled the system with a new graphics card, and the issue was gone. Another computer repair mystery was solved.