If this particular Dell model has had a history of trouble with heat and fan noise and cycling, there may not be much you can do. Check Dell's site for BIOS updates, particularly for fan and/or control. Ages ago, I had a Dell Inspiron 8100 laptop, and the noise from the fans was like being behind a jet. At first purchase, they cycled and were loud all the time. Then after Dell addressed the issue with an update, they cycled rarely, and went into high-speed mode only under duress.
Their current BIOS for this model is A17. Version A11 fixed some thermal control issues. Check your BIOS version.
Hard to advise about a new laptop w/out more requirement info. There are *plenty* of inexpensive models that will run with lower power, low heat, and hence silent.