I think the safest thing is really to test it at the guy’s place, man. While you’re at it, check what he has installed on the PC, then you’ll know if he really uses it for games or for something else that puts a heavy load on the card.
I forgot the name of the program, but install that program that shows the card’s temperature, how many percent it’s using, and the FPS. But the main thing is the temperature.
Ask him if he changed anything. If he did overclock or something else.