The oldest I have, is a late-socket-775 system, the Asus Maximus II Gene, which is from 2009, which I got used in 2013. I have some Core 2s, mostly 45nm.
TMK, the latest Asus socket 775 motherboard to use DDR2!
The only way to tell, is to try it. I won't be able to tell if that sample OCs better than the Q6600 I possibly still have sitting around. I would be able to tell, major-fast, if it's a better OC'er, because I've been testing the one that I got used in the mid-2010s, and that's the one that unfortunately has bus error issues at only 367 MHz.
But, I went to focusing on 45nm Core 2 OC'ing.