How long does a power supply last?

People ask me all the time what the most important part of a computer is, after they find out I work with computers. And I always surprise them when I say the power supply. Your computer is only as stable and reliable as the power supply. But how long does a power supply last? Of course it depends.

A good name-brand power supply can last many years. Cheap power supplies, in my experience, typically start giving you trouble within three years. Paying double for a power supply doesn’t necessarily guarantee double the life expectancy, but the odds tend to be pretty good.

Signs of a failing power supply

how long does a power supply last?
If you open a cheap power supply, you often find a lot of empty space inside. Better units generally use components that take more space and weigh more. And you can expect the better power supply to last 2-3 times as long.

Power supplies rarely fail right away. It’s only happened to me once, and it confused the technician I enlisted to help me too. Not only that, the time it happened was with a Corsair, a brand I recommend.

Typically, even a cheap power supply happily powers your system for a while. But eventually, as the components wear out, the system starts acting up. It may fail completely, and fail to power the system up entirely. More frequently, the system reboots spontaneously and unexpectedly, or the screen freezes up and stops responding to keyboard or mouse input.

If it just happens once, I’m probably not going to start changing hardware. But when it starts happening a lot, the power supply is one of the things you need to suspect. The problem generally doesn’t get better on its own. Early on it might happen once a week, but given enough time, the system doesn’t make it through the day.

The temptation of saving $20

Not all $20 power supplies are necessarily the same. But I’ve bought a few of them in my day, for various reasons. Maybe I needed something in a hurry and that was all I could get that day, or I didn’t have the budget that month for a pricier box. Or the price is just too tempting and I can’t fight off the temptation. Unless the box is woefully underpowered and I try to ask far too much from it, I can get 2-3 years out of one. Sometimes a bit more.

These days you can get a no-name 400-watt power supply for $15 or a 500-watt box for $20. At that price, it’s tempting to see if you can get three-plus years out of it. I’m not saying I recommend it. But I understand why it’s tempting. And I do have better luck with today’s cheapies than I did 20 years ago.

How long name-brand power supplies last

It’s not hard to find people who say their preferred power supply brand lasts 10 years. And sometimes they will. I’ve seen them. But I’ve also seen them fail after about five years. When I want reliability, I pony up for the name-brand box. It won’t necessarily last twice as long as the cheap econobox, but in the worst case scenario it should come close. And in the best case scenario, it can last three times as long. You break even if it lasts twice as long, and you come out ahead if it lasts longer than that.

At those kinds of life expectancies you do run the risk of obsolescence, but the days of each processor generation having major changes to their power requirements do seem to be over. In the event of obsolescence, it’s easier to resell brand-name hardware to someone with an older system than to sell no-name hardware. Sell it early enough in the changeover cycle, and you can minimize your losses.

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