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?
Yup, reset the CMOS. You should have a jumper on your board to do that or you can just remove the small round battery for a minute and then put it back. Anyway, the thermal diodes on those two cores could have been defective which is why it wasn't sold as an X4.
Thanks for the reply! I was able to successfully lock it today morning by getting into BIOS, CPU Config and I turned off manually the extra cores while I had Unleashing enabled. I saved BIOS, rebooted. Then again went into BIOS, disabled ACC altogether, saved and rebooted. It seems to have locked the extra cores!! Also with the cores locked, I read CPU Core temps in speedfan which shows the cores idling at around 38 (I live in south India where room temperatures reach 40°C in the months between April and July. But for some reason, the socket sensor on my ASUS board seems to read ~49°C at idling. May be the sensor isn't giving proper voltages. But I am happy things are back to normal!! And the good thing is I am lucky to have a working quad core Phenom for which I paid only $90!! Need to change the HSF, unlock cores and overclock it and find my sweet spot for everyday use!! Wish me luck guys!!