ProLiant DL160 G6 CPU upgrade

I want to upgrade the CPU's in my HP ProLiant DL160 G6 from the Intel Xeons L5630's to more capable ones, but I'm worried about the TDP, as the heatsinks are sort of small, it being a U1 rack server. I was looking at 6 cored ones with TDP's of 130 watts, and I was somewhat skeptical of 130 watts on the tiny heatsinks. Is there a larger heatsink option available or a rated TDP for the stock heatsinks?
Joshua.