ASUS M4A77TD / Phenom II 555 unlock no boot

Good morning,
I am new at this so I will try to be as detailled as possible.

Problem:
when I enter the bios and set the ACC to auto and then try to unclock the cores by selecting unleashed. I then exit the bios and it reboots the system as expected. The screen message for the ASUS bios loading appears (one white line of text on black screen: normal) and instead of then going to the ASUS bios screen (large ASUS logo on green background, press 4 to unclock cores, press DEL to enter bios settings...) all I get is a black dark screen. The PC runs but does not load. All I can hear is the fans running.
Nothing else happens and if I switch the PC off, the same thing happens again.

All I can do is flash the bios directly on the mobo with the jumper directly. At that point, the bios default settings are back and the PC boots as a normal 2 core CPU.

Question: why is the board doing this? Is this normal? Should I have waited longer for the cores to unlock? Does this just mean the 2 hidden cores are so unstable/broken they cannot be unlocked?

I bought this CPU because it seemed like a good deal for $100. I don't need the unlocked cores nor did I buy it for this reason. However I expected that if the cores were bad my system would just be unstable. I did not expect that it couldn't even boot up. Therefore I am wondering if this is not the CPU but the motherboard?


Details:
Bios: most recent bios was updated. I did that last week.
Overclock: none so far
ASUS M4A77TD AM3 AMD 770 ATX AMD Motherboard
AMD Phenom II X2 555 Black Edition Callisto 3.2GHz Socket AM3 80W Dual-Core Desktop Processor - C3 Revision Model HDZ555WFGMBOX
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9D-4GBRL
4 answers Last reply
More about asus m4a77td phenom unlock boot
  1. Hi newcomer and welcome to the Tom's hardware forum.

    Ur problem usually means that the hidden cores aren't stable when u unlock it.
  2. He's right. You are better off with the stock cores.
  3. Thanks a bunch.
    It is good to know that was just it.
  4. Im not sure but I think the C3 revsion may have something to do with it. I had a Phenom II X3 710 and unlocked 4 cores just fine. But like I said im not sure.
Ask a new question

Read More

CPUs Asus BIOS