i've bought a Phenom X2 555 BE processor, along with an ECS A790GXM-AD3 motherboard... once installed the processor and the rest of the components, i installed Windows XP SP3... and then the problem starts:
Windows Task Manager shows only one core and CPUZ also shows only one core, but the device manager shows 2 processors (2 cores)... beside that, i tested the mb with another processor of the same type, and the processor itself with another mb (a cheap one from ECS), and there was no problem... even i asked the technician to test my mb with my processor... and everything was ok!
but... at home...
Specs of my pc:
Phenom X2 555 (normal 2 cores)
ECS A790GXM-AD3 (integrated Radeon HD 3300)
Samsung DD3 2GB 1066
Hitachi Sata2 164gb, Hitachi Sata2 320gb
PSU Logisys Black Beauty 550w
And if you ask, task manager doesn't show more options to see graphis per core.. the only option is to show one core...