Well, after a lot of voltage adjustments, it appears my Giga upgrade is now stable at 1.2 GHz. According to Giga customer support (which is excellent, by the way), every Cube is slightly different, thus the need to sometimes fine tune the voltage. I am running at 1.55 volts; it would probably be fine without a fan, but I intend to add a slow-moving fan to be on the safe side. In the meantime, I have placed an external fan under the Cube and the air blowing out the top feels less warm than a stock Cube. Sorry about the non-scientific measurement... To answer the earlier question, the Giga card comes with a large copper heat sink (aka thermal transfer plate) that gets screwed to the Cube's black finned heat sink. When I pull the core, the copper sink and the black sink both feel only slightly warm to the touch. All in all, I am satisified. No wake from sleep problems, and MUCH faster than 450 MHz. And if it turns out that the fan bugs me, I can definitely go back to 1 GHz or 1.1 GHz and run without a fan.