First after getting the Error: ROM file size incorrect I searched it and found that it was a problem due to and update not for that motherboard. Apparently ASRock has all his BIOS updates in a single page. Source : http://www.ddpsystems.com/bios_tech.html
After that, I downloaded every Bios Update until i got one that worked (P1.30 for Windows), Updated it and then installed the new CPU. (I'm working with it right now).
So that's all it was just a BIOS update Issue. Thank You very much again for your help, Z1NONLY.