ok i have just tested out
seems that only il2 cod russian version i got with steam and DCS A10C were affected with the cpu change: now i have il2 cod:
1 activation left (how generous!!!)
and DCS A10C:
6 activations left
Armed Assault II didn't bitch about the "significant" hardware change and all the DLC's i have with it (AO, BAF, PMC) started normally through Steam as well
in fact, i should have had deactivated them before swapping cpu's