I helped a friend with cooling of his ACA620, although not to overclock but get stable operation in the environment which it was in. Anyway here's what was done:
First we went though a bunch of chipset coolers we had at hand and finaly went with a nice
Revoltec Chipset Cooler because of the integrated fan with still a low profile aswell as it's almost matching color to the ACA card... almost any chipset cooler will have same hole spacing so don't sweat it if you can't find this exact one.
Next was to cut a piece of aluminum to size to use as a
shim. The heatsink was a bit wobbly so, although probably overkill, we added some
foam pads around the hole for good measure.
Now come the modding of the ACA board itself slight. The holes the heatsink utilize had to be widened from 3.0mm to 3.5mm using first a 3.2mm and then a 3.5mm drillbit (
gently hand force only). The "upper right" corner of the CPU sockets leg protruded a bit too much though the PCB and came in contact with the heatsink, with a slightly thicker shim this problem would not exist but it was solved by
shortening the legs.
Final result.
