CoOkie

So how long after you fitted your silencer kit did it go? When you installed the new silencer kit, did it involve taking off the old heatsink? If so did you clean the cpu before fitting the new heatsink...? (I'm presuming the kit included a heatsink and fan) You said that you noticed the fans were more active, this could indicate that heat was an issue.
I use TIM fluid (Akasa) to clean the old paste residue off the cpu and heatsink.
Funnily enough I serviced my friend's pc today which involved cleaning the cpu and heatsink and when I put it all back together and went to switch on, I got nothing. I opened it up again and found that I'd actually put the heatsink the wrong way round; so I corrected it and it booted up straight away.