I just received an E6420 billed as an i7-2720QM, 4 Core CPU. I'm almost certain that when I viewed the BIOS it also identified as such.
I upgraded the BIOS from A01 to A05, and then form A05 to A24. Now, the machines current configuration identifies the CPU as an i7-2640M 2 core CPU, but with a -4 appendix, as if the machine knows it has 4 cores. I would like to know once and for all what I actually have without disassembly.