I realise there is an older thread on the very subject but that seems to be pretty dead.
I just got a Dell Studio XPS 1645 laptop and the fan noise and overheating is pretty ridiculous. This is actually a well known problem with the laptop that is apparently solved with the combination of a BIOS update and the purchase of their 130w charger. I plan on buying this charger as soon as possible, however I've noticed that since installing Ubuntu the fan noise has became more permanent and the overheating is quite a bit worse too. I've had to turn it off twice to let it cool down for an hour or so because it starts seriously affecting the performance. It makes watching things, listening to music or leaving the laptop on while I sleep a real pain.
If anyone has some new information on this issue or could help out in anyway at all I'd be very grateful. Thanks.
EDIT: I installed Windows to see if the problem was worsened by Ubuntu and sadly it seems so. It's still quite noisy but the temperatures are staying at a steady, much lower rate. Staying on Windows is something I'd definitely prefer not to do.