oh shit,you have the 955 x4.that being the case then you do have a true quad-core cpu and it would be no problem overclocking that one.in fact,you could even get it to pit up the same numbers as the 965 without overclocking or adding a bigger heatsink to it.when it boots up,go into the bios and configuration of the board,cpu,and ram.once there,set the multiplier to x17 and surprise,you literally have a Phenom II x4 965 Black Edition that runs stock at 3.4Ghz without having to spend the extra $75 or so on it,lol.also,if you're going to overclock it,i would HIGHLY recommend you getting a better heatsink that what came stock with it.i would go with something like the zalman cnps10x or cooler master v8.it just all depends on the size case you have and then how much room inside that case you have to spare.plus,if you're going to be reaching for crazy Ghz,then you need to also look at a water system.i myself am getting ready to install the zalman reserator XT BK on my new build.the number i told you that AMD was recorded at,actually was at 6.3(my bad),was with liquid helium and liquid nitrogen(-232 Celcius).here's the link to that video:

http://www.youtube.com/watch?v=wB0JodKgZ0A

the actual numbers from the tests were:
3D Mark 05:45474
Speed:6301MHz(6.3GHz) on all cores @ 22.5x280MHz
Voltage:1.840V
Northbridge:3920MHz(3.92GHz) CPU NB clock @1.425V

good luck!!!