your cpu is sandy bridge based, listed cpu is an ivy bridge processor, chipset largely supports only sandy bridge processor,
this link says a select few ivy bridge are supposedly usable, but i wouldn't count on the laptop saying its all good.
i would think an i5 2430m or so would be an achievable upgrade, steps up the base freq a little and give turbo to 3ghz.
a post on the lenovo forum says the i7 2620m is listed in a manual for an upgrade...
probably drinking some tea.