If it's on your P3V4X, the Alpha PEP66 would be a good one.
edit: it's especially good for use on slockets, and I'm assuming you are running a slocket here. If not, look at the VOS32 and replace the two 60mm fans with a quiet 80mm fan. On the PEP66, the fan makes the air go all the way through the heatsink, so even if you have a quiet, lower-output fan, the middle of the heatsink still gets airflow. You can buy the heatsink with a powerful fan and lower it from 12 volts to 7 volts, if you want. This is a nice trick with the 27cfm YSTech fan. Or you can get it with a low-rpm, quiet fan. The heatsink itself has a copper heat-spreader base.
millisec.com sells the PEP66 with the YSTech fan or a lower-output Sunon, and I like the YStech better, since it is about the same percieved noise level and gives more airflow.
plycon.com has the PEP66 with the quiet-running Sanyo Denki fan, I haven't tried one but people are saying it is very quiet.
phamcomputer.com has the PEP66 with the ultra-quiet Adda fan or a high-output Adda.
2Cooltek.com has the PEP66 with the Sunon fan.
I saw that millisec also has the FOP32 on special, it is the version with the lower-pressure clip intended for FCPGA processors, and it will be more versatile in socket applications that the PEP66, if you end up moving on from the P3V4X and need to reuse it.
FOP32 on sale for $18 with YSTech 27cfm fan
Like I mentioned, you can run the fan at 7 volts and get decent airflow, I estimate about 18cfm, with a lot less noise. Just ground the fan's black wire to the power-supply harness's yellow wire.