Hi I bought a Phenom II X2 555 Black edition two days ago along with an ASUS M4A88T-M-LE Motherboard and 1 x 4GB DDR3 1333Mhz Kingston memory for a replacement PC. I run with BIOS ver 0304 with which I was successfully able to unlock and run windows. CPU-Z reported correctly 4 cores. I run windows XP 64 bit and just to test how things are for a few minutes, I played UT for a some 10 mins. Then I wanted to check my CPU core Temp, it did not show as expected!! I checked that CPU showed 48° C in Asus PC Probe with 4 cores idling. This was with stock heatsink fan. I decided to install the Cooler Master Hyper Tx3 which I had purchased on the same day. Before I could do this, I wanted to see thermal performance with the new heatsink fan. SO I decided to lock the 2 extra cores. I disabled Unleashing and the ACC in bios and saved it. Rebooted. It still shows Phenom II X4 and did not revert to Callisto core in CPU-Z inside windows. How do I do it?