Hi, Newbie here.
I'm upgrading a Dell 4500 for my daughter, I've installed more Ram,bigger HDD and a network card. It runs well........But with a problem. I keep getting a fan faliure message before i start and then shut's down after about an hour or so (due to thermal event ).
I checked with the previous owner ( her Grandad and he had the same message in it's original state.

Can i still buy new fans for them? and where from? is there anything else i can try?

Thanks

Did you check to make sure that the fan is running? If not, that'll do it.

If so, check if the fan has two or three wires running the fan header on the board. If it's only two wires then there is no feedback from the fan to the PC, three wires would be +, -, and RPMs. If it's expecting feedback for some reason and isn't getting any, that might cause the fan error but it doesn't seem like it would set the overheat flag and cause it to shut down. The fan actually not working would, however, as it really would be overheating. Faulty temp sensors may also cause the problem.

Get a voltage/fan/temp monitoring software like SpeedFan to monitor what's going on in there and if the temps really are getting up past the failure point.

As for buying new fans, they're readily available at places like New Egg, Tiger Direct and DIgiKey