A friend bought a new computer this month. It arrived sooner than expected, and she called to ask what she should do. I said, among other things, to set it up and leave it powered on continuously for at least 24 hours.
A coworker who had never heard that advice asked why.
The reason is twofold. If a machine–electronic or otherwise–is going to fail, it’s more likely to do so very early in life. So running it for 24 hours will expose any parts that are due for premature failure. If the device survives its first 24 hours, odds are it will run for years afterward. But the second reason is called oxide healing. I can’t find a good link outside of electrical engineering textbook excerpts on Google Books, but basically, if any of the tiny electrical traces in computer chips (made of one exotic metal oxide or another, hence the name) are questionable, sometimes running continuously for a length of time conditions these traces and makes a borderline chip OK.
I do a burn-in on every computer I build. I’ve been doing burn-ins on my new computers for 20 years, and I rarely have hardware problems. I average about one hardware failure every five years, and that’s spread out among multiple computers. I do a burn-in on any other electronic device I buy as well, for the same reason.
Ideally, each chip should get a burn-in at the factory, and the complete device should receive a burn-in after final assembly, but that doesn’t always happen. Doing a burn-in yourself gives yourself some extra insurance, at minimal cost and effort.
It’s certainly not a bad idea to stress test your hardware, and frankly, I’d add a regimen of SpinRite to that list to make sure the hard drive starts its life out on the best foot possible. But if all you have the time and effort to do is power the PC up and walk away for 24 hours, that will give you most of the benefit.