Here’s a good question: Will running Prime95 void my warranty? I have the answer to that. I run Prime 95 on every new computer I get, so that probably tips you off.
The short answer is no, and, in fact, I ran it about 30 hours straight on my newest computer. I started it on Friday before I left for work. I let it run until I got home from running errands on Saturday. All told, it probably ran 30 hours. If a computer is going to fail, I want it to fail before I’m depending on it for something.
In fact, there’s not really any way the store or manufacturer can tell you’d been running Prime95, anyway.
I’ll tell you why I believe in stress testing, and not just simple burn-in.
I used to support a large, distributed, web-based application for a living. We had a couple dozen database servers distributed throughout the world. Once a year we’d upgrade the custom software. The upgrade involved huge numbers of database transactions that would force the database servers’ CPU usage to 100%. The CPUs stayed pegged for the better part of the week. And, every single time, at least one of those servers would fail spectacularly during the upgrade.
Those servers were never stress-tested before they were deployed. They should have been. They also should have been stress-tested a couple of weeks prior to these upgrades, to make sure they could still handle running under load. Computers do tend to degrade over time. Make the servers fail ahead of time. Direct the users to other servers, of course. Then stress test and repair or replace anything that breaks. Then the upgrades would go much more smoothly.
Your desktop PC doesn’t undergo the stresses those database servers did. But a thorough test on your part during the first day or two of ownership will make up for any poor quality control that happens through the supply chain.
Whether I built a computer or bought it, and particularly if I bought a really cheap computer, I’d Prime95 the living daylights out of it. Once it can handle Prime95 running full tilt, I know what I have. And I know I have something good.