Doesn't sound strange at all.

Such machines appear in the shop all the time. The funny thing (at least to the tech) is how many folk say it's not overheating. And then we clean the vents and heatsinks, and maybe replace heatsink compound, a power supply or board or find some corrupt OS.

The constant so far is it's rarely the same thing except that folk don't keep the vents and such clean.

Bob