I am attempting to upgrade my Dell GX620 on the cheap. It currently has the Intel Dual Core 2.8Ghz and is only upgradeable to Pentium D 3.2Ghz as far as I know, which is a minimal upgrade. After some research it appears that it is possible to swap motherboards and put a GX745 motherboard into it, thereby opening the doors to the Core Duo processor class. By all appearances it looks to be the same Dell form factor, and the 745 motherboard was only $25 on ebay. I am curious how problem free your Q6600 is running, and whether I should be looking for a Core 2 Duo or Core 2 Quad. It appears that the Q6600 are selling for less on ebay than say the E8600 Duo, but I want to make certain that there are no low voltage or heating problems with the Quad given that the Optiplex Dells have small power supplies. Any advice or recommendations would be much appreciated.