Press delete, escape, F1, F2 or F10 to get into the BIOS when booting.
Watch for a screen that says "Press (key) to enter BIOS or SETUP" and press the key specified.
If all else fails, turn it on and just keep tapping escape, delete, F1, F2 and F10 until you get in.
Then look for the temperatures, they are in a different place in each BIOS.