No, you cannot change thermal settings in the BIOS, and you would not want to unless it was to increase your fan speeds to help lower the temperatures. Vendor systems built by companies like Dell and HP do not allow BIOS changes to thermal or fan settings. You should check whether it is a dust issue, first, as
seavixen32 said.
- Shut down and turn off the system,
- unplug the system from the wall and ac adapter,
- remove the battery,
- and hold down the power button for 30 seconds to close the circuit and drain residual power.
Then work on getting the dust cleaned out with a can of compressed air. Just blow the air into all vents, usb ports, vga ports, etc., and into the keyboard. Then replace the battery followed by the AC power and turn on the system. See how it responds.