Cupboard cooling issue

[pmbuzz]

This may sound strange….

We have a pc that is situated inside a cupboard (it has to stay there)
We have added air holes to allow heat to escape but it still overheats from time to time, causing issues.

My question is, can I install fans inside the cupboard that will expel the hot air out …. If so, which fans are recommended.

Apologies for what seems a very basic question

 

[Werewolf]

You can indeed fit fans to remove the heat from the cupboard.
You could use case fans connected via molex/sata or even motherboard headers (with an extension cable, or via a fan controller that can take the speed control for one fan and use it to control several), the motherboard connector option would mean the fans could be controlled by the motherboard so spin up/down as demanded by the PC.
The other option is to either fit mains powered fans, or case fans connected to a separate power supply and possibly connected to a thermostatic control of some type.

The first option is probably the easier one to run with in terms of no additional power sources needed, but may cause a few issues when you go to pull the case out of the cupboard, the second is totally independent of the case but probably a bit harder to have it temperature controlled.

Remember, like the case itself you'll want intake holes (low down) as well as the exhaust holes, it's even possible that simply adding the holes will be enough on their own if the cupboard doesn't have any ventilation at the moment.
If you do need to add holes in the cupboard, I'd suggest getting a half decent holesaw in the right size, they're not massively expensive and will likely save you a lot of time or cursing as you try and make a suitable size round hole.