I have tried replacing my heatsink and fan many times now , but
non if the new heatsinks were accepted by the motherboard.
When I try to boot the power goes out after 1 or 2 seconds.
The board is Asus A7V333 and the original heatsink is longer than
all the new ones , raised allowing it to cover most of the plastic
under which the sockets lever is attached. This raised area has
2 slits that are almost covered by the original heatsink so I hoped
there were light sensors there but that does not seam to be the case.
The detection doesn't even involve the heatsink clamp being in place
since just placing the heatsink on top of the CPU seams to make it work.

Any other possibilities?

I would like to close this up since besides knocking on the fan
I have no other reason to keep it open.
The Atholon 2100MHz has always been running at 1300 since I got it
second hand because it was getting way too hot.
But even then if in C&C on a hot summer day....
Until I cleaned up the area of old heat transfer pad , old paste
and newly applied Stars 700 heatsink compound that I got almost
constant 60C (oops 52 now but I haven't played C&C )

So best transfer with nothing on it.

Cheers