This is the #1 power-on failure. The manual identifies: faulty 12V CPU power connector (4-pin ATX12V) or shorted motherboard mounting screw. Remove board from case, test on cardboard.
support 3rd Generation (22nm Ivy Bridge) CPUs like the i5-3450 without specific BIOS updates, though some sources mention mixed compatibility. : Four DDR3 DIMM slots. Maximum RAM Lenovo Is6xm Rev 1.0 Motherboard Manual
Detailed schematics and maintenance guides for this board can be found through professional archives: This is the #1 power-on failure