the Phenom II is incompatible with that unit, now if there is a BIOS update then I would look for it.
with BIOS update you might get lucky and board will flash to AM2+ ability for chips.
I currently am not speaking about any TDP limitations for that motherboard because it seems it can run the first Gen of Phenom chips
just not the second Gen and that's what the Phenom II is...http://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en&docname=c01635734#N92
as you can see the mobo is a first GEN AM2 board.
it's time to upgrade the board as well, not just the CPU.