C533 ppga on a BH6. A constantly evolving project. Latest is a cooling block made from a brass case siliconed and chemical metalled directly to a 60W peltier. An extra 5 degrees colder. Cooling water has direct contact with TEC hotside. The water is run outside to a car heater core, with the original fan. CPU temp under load (Seti) on a warm (25 deg) day is 6-8 degrees@2.1v. Posts at 800Mhz with 2.6v but locks immediately. Waiting for a -25 degree winter day. :) Update: Some irritating summer condensation problems lately have caused a spate of insulating attempts. None work terribly well due to the difficulty of getting at the slotket. New approach! Put in another cooling block attached via a small 32W peltier to the original heatsink + fan and put the case covers on for the first time in years. Very effective dehumidifier. Early results are very promising.