Okay, I'm hoping someone here has an idea about what's wrong with my Mini. I have a 1.66ghz Core Duo w/ 512 of RAM. I upgraded to a 2.33ghz Core 2 Duo with 2gb of RAM (I initally did 4gb but then realized that I have the 1.1 version of the Mini firmware which if I understand rightly can only accept 2GB of RAM). So I do the upgrade and start her up and... nothing. You can hear the hard drive's initial start up, but then quiet. Power light is on but no video output - just a blank screen. I did try both the PRAM and SMC reset (and I did do the intel version not the PPC version) but sitll no luck. Now this is where it gets weird. I put back the original processor (1.66 core duo) and RAM and everything worked fine. So, I put back the 2.33 ghz processor, but did not reattach the heat sink because I did not want to keep having to take it off if I needed to switch back the processors for fear of breaking one of the plastic posts. So here is a breakdown of results: 1. 2.33 processor/original RAM (512 total) with no heat sink attached. Mac mini boots up fine with no problem. Max fan noise. 2. 2.33 processor/new RAM (2GB total) with heat sink attached. No boot and no video output. Power light is on and you hear the initial hard drive start up but that's all. PRAM zapped. 3. 2.33 processor/original RAM with heatsink attached. PRAM zapped. Same result as #2. 4. 1.66 processor/original RAM with NO heatsink. Same result as #2. PRAM then zapped and Mini boots up no problem. 5. 2.33 processor/original RAM with NO heatsink. Mini boots up with no problem but with max fan noise. 6. 2.33 processor/original RAM with heatsink installed. Same result as #2. ARRRRGH!!!!!!!!!! I am at wit's end. Unless there is some brillant, insightful help amongst the genuises that populate this forum I guess it's off to an Apple service center for me and my Mini.