Call Dell and have the fan replaced under warranty.

We received 2 brand new E7240s directly from Dell, one for myself and one for my colleague. As soon as I turned it on to build it for my colleague, I noticed the machine was overheating and the fan was making a noise. Dell suggested a BIOS upgrade which didn't change anything. They then changed the heatsink, again this changed nothing and since then they changed the motherboard. My colleague has gone on holiday so I don't know if her issue has been resolved, however, my new E7240 from day one does not overheat BUT THE FAN TURNS ALL THE TIME. So much so that I think the person in the upstairs bedroom is using her hairdryer. Dell replaced the heatsink and the motherboard yesterday, I have done the same BIOS upgrade and the problem is even worse. As soon as I switch the thing on, the ventilator turns all the time making a loud noise. My previous model was the E6500 and I wasn't bothered by any noises it made. The 7240 makes so much noise that I want to throw it out of the window, seriously I am going to switch back to my 5 year old e6500 which is now very slow, I just can't take the constant hair dryer noise from the fan!