Antwoord op "I am thinking of upgrading the current Core 2 Duo 3.33GHz to Quadcore"Well... since you're obviously willing to scrap the warranty anyway, I'd try to overclock the 21.5's E8600 (the 3.33 core 2 processor) first before I'd try to swap the chip (which could be both a heating and a compatibility issue). That particular Core 2 is the badest Core 2 Dual ever made. PC users have overclocked it to 4.00 ghz, 5 ghz and beyond. The iMac is a tight unit, but you might be able to safely overclock it through software by a few percentage points and see how it goes. If you are mechanically inclined, you might even find a way to improve the cooling system in the iMac.