Thanks for the replies everyone.
@Blackswan122 thanks for the experiment! So there is not a huge difference in money earned between the two prices. I think if I had it at home I would definitely go for a fan, but at work it is tricky.
I bought a little heatsink for a couple of quid. May make a small difference...
After reading everyone's replies I think we can be pretty sure there will be no fire - that is good to know