You are out of luck ... the nVidia nForce MCP61 chipset is too old for unlocking (it dates back to 2005-2006). The nForce 7-series evolved with some unlocking potential but not at the level of the AMD AM2/AM2+ motherboards with the correct 7xx South Bridge.
The Sempy 140 single-core CPU is an AthlonII x2 dual-core processor. In order to unlock that second core you need to engage the 'ACC' function in your motherboard BIOS ...
This is on a Gigabyte 785G AM2+ motherboard ---
The 'unlocked' processor becomes an X2 440e, and can typically take a sweet OC ...
as for AMD, some CPU especially atlhon 64 x2 / phenom II sometimes where just chip that had problem with some core but the some mobo could unlock core so that it would be a 3 or 4 core
You are out of luck ... the nVidia nForce MCP61 chipset is too old for unlocking (it dates back to 2005-2006). The nForce 7-series evolved with some unlocking potential but not at the level of the AMD AM2/AM2+ motherboards with the correct 7xx South Bridge.