I was asked to look at a PC which was misbehaving. Sometimes it worked, but increasingly it was freezing or crashing. Sometimes the hard drive would corrupt and needed Windows repair before it would boot.

I took a look. I ran the drive manufacturer’s diagnostics, which reported no drive errors. I ran memory tests. I removed each of the two RAM sticks alternately to see if one was faulty. I tested the power supply. The PC was still not stable.

Then I took a close look at the motherboard. The only visible sign of possible trouble was that two capacitors close to the RAM sockets were bulging slightly at the top.

I removed the board and replaced the capacitors – not that easy a task, though the actual capacitors are cheap enough. You need a powerful soldering iron and plenty of patience.

Since the replacement though, the PC has been perfectly stable.

Of course the owner had presumed a Windows problem and spent ages updating drivers, looking for viruses, and so on.

The capacitors are branded Tk and since making the repair I discovered that others have similar tales. It is not just these specific capacitors though. The bad capacitor problem remains a common fault with PCs that are a few years old.

The economics of the repair is marginal unless you can do it yourself. A replacement motherboard costs so little that it does not pay for much professional service time. However if like me you get some satisfaction from repairing rather than disposing of old but good electronics, it is worth it.

The other point: if your PC is crashing a lot, take the back off and check the capacitors. Any bulges or leaks, and you can stop wasting time trying to fix a hardware problem by tweaking Windows.