thats a lot of juice
i would want to be building a PWM controller, do you have any experience in power electronics?
are you driveing this from your PC PSU ?
if you budget will allow id use something like the m-cubed tbalencer
use this to create a PWM signal with a custom profile based on ambient temp and proc. temp sensors. Id then input this into the base of what is esentially a power amplifer, a suitably spec'ed darlington driver / mosfet (s) that can cope with the current you need, As your not driving an inductive load the circuit would quite simple, with a little care and posably a couple of capacators to smoth the current draw from then power supply and delivery voltage you can have very low power loss control of you pelt / cpu temp tuneable in windows and microprocessor controled.
if your really interested ill pull out some of my old 3rd year electronic eng. notes and spec up some components / sugested circuit total cost shouldnt be too much.