What PC case is sturdy enough to sit on?

The Phanteks Enthoo Elite has a very substantial frame and could probably handle some weight, but I wouldn’t treat it as a chair—especially for anyone above roughly 150 pounds. A used Corsair Vengeance C70 is another famously rugged option if you can find one.

A proper chair is probably the safest and cheapest solution. Even a very tough case may have panels, vents, or internal components that can bend under repeated weight, and sitting on it could also restrict airflow.

The Havn 420 is unusually heavy and solid, so it might tolerate someone sitting on it better than most cases. Still, check the manufacturer’s weight limits and avoid putting your full weight on removable panels.

If you really want a PC that can function as a seat, look for a custom enclosure with a reinforced steel top and the computer mounted away from the load-bearing area. Standard cases aren’t designed for people to sit on, so a chair or a purpose-built PC-seat setup would be much more reliable.