socket m

The Socket M can only support:

Intel Core Solo
Intel Core Duo
Intel Core 2 Duo (T5x00, T7x00)
Intel Celeron M

Socket P:

Intel Core 2 Duo (T5xx0, T7xx0, T8x00, T9x00)
Intel Celeron M
Intel Pentium Dual-Core (T23x0)

http://forums.lenovo.com/t5/R-and-L-Series-ThinkPad-Laptops/Upgrade-Pro…