Havok does need 6 cores

IDF 2010: Makes a difference
As Intel owns Havok, it focuses on up to six cores, as it doesn’t actually offer more than that, at least not in desktop CPUs. Nvidia on the other hand preaches more than six cores as it has hundreds of multithreaded cores in its GPUs.
The chap from Havok, Intel’s integrated part for graphics, showed off some nice cloth animation on multiple cloned trolls or dancing ladies. It looks good but we believe that graphics on a discrete GPU can do much more.
It is a fight for the physics market between Nvidia and Intel at the moment and AMD seems to be sitting this round out.