PC won't boot to bios or windows

Hello everyone, today i was testing around bios setting to unlock the hidden core of my AMD Athlon x3 II 2.7ghz 425 and make it to a AMD Fhenom II x4 2.7ghz B25. I succesfully did it but after unlocking the hidden core my pc won't boot to windows. So i decided to reinstall windows with my setting in bios making my cpu to a better cpu. After reinstall windows, Windows lags a little and often stuck and had to reboot. I think maybe it was cause because of the bios setting, so i boot into bios and i want to revent back, in the process i found out that i input a wrong setting in the beggining when i was unlocking the hidden core, so i made some change to the setting and cancel the idea of revert back. After made the changes it reboot but display does not showing up and no beep sound, i wait a couple of minute but still nothing. I think mayde because of the setting, it broke the CPU. I swith of the computer,took of the cpu cooler and put 2 finger on the cpu, turn on the pc and i feel the cpu warming up.Just for 2 second and then i turn off the pc. So it was not the cpu and right now i dont no what is causing this problem. Sould i replace the motherboard or cpu or both.

specs:
CPU:AMD Athlon II x3 2.7ghz 425
Mobo:Gigabyte GA MA74gmt-s2
Ram:4 GB kingston 1333mhz
GPU:Gigabyte HD 7750 OC
PSU:Basic atx nothing fancy
HDD:WD caviar blue 160GB Sata II
Samsung 22x dvd drive
Samsung 20inch monitor 1280x720

Thanks in advance