Testing

Testing was a simple process and consisted of monitoring the CPU's temperature while at idle and load, and comparing the results of the Type II Cooler Master CB5-7KFSA-02-GP to the results of the Type I Thermaltake CL-P0191.  An external thermometer was used to monitor ambient conditions, and one of the two LCD thermometers installed in the 5.25" bay was used to monitor the temperature of the processor.  The thermometer lead was affixed to the base of the cooler with tape, with the very tip of the lead bent to be up against the raised copper core.

Idle conditions simply involved having the system sit at the Ubuntu desktop with nothing else running for a period of at least one hour. Load conditions involved having the system run two instances of Folding@Home to fully stress each of the D840's two cores to 100%, and this was also run for a period of at least one hour.  This process was executed with the Cooler Master CB5-7KFSA-02-GP installed with the thermal pad intact, with the Cooler Master CB5-7KFSA-02-GP wiped clean of the thermal pad and using Thermalright's new Chill Factor thermal paste instead, and with the Thermaltake CL-P0191 installed with Chill Factor paste.

The chart below summarizes the results recorded while maintaining an ambient temperature of 20 degrees Celsius:

As you can see, things were not pretty with the stock thermal pad installed!  Although I never had an issue with system stability, the high temperatures did make me nervous.  Additionally, I was able to shut down the PC safely every time I wanted to, but upon each start up I would be presented with BIOS beeps and a message that the system had been shut down due to thermal issues.  Not a true statement, but one that made me nervous anyway!

Switching to the Thermalright brand thermal paste improved things greatly.  Temperatures dropped closer to those achieved with the Type I cooler from Thermaltake.  They weren't quite as good, but close, and mostly had to be due to the higher fan speed.  The Thermaltake fan never went above 1500 RPM, while the Cooler Master cracked 3000 RPM at full load.  I do not understand why these fans don't go faster at such elevated temperatures!  If a fan is rated to 7000 RPM, it should be at full speed well before it gets to 65C! 

One thing that did not improve with the Thermalright thermal paste was the BIOS beeping and error message upon start up.  I am still faced with the message regarding the system shutting down, despite the better temperatures and the fact that the system has never actually shut down.  One area I will be investigating is the motherboard chipset, as a thermal probe on the base of its cooler indicates that it gets over 70 degrees Celsius with ease.