What makes you think the board can handle the Phenom2 X3 715 or the Phenom2 920? I cannot find the M3A78-T on the ASUS website, so I asume it has the lowest spec of any of the M3A78 boards them do list, the M3A78 PRO, just to be sure. That means yes, it will take the two CPUs you mention on all PCB version, BUT the bios has to be at least 0902 for the 715 and at least 0702 for the 920. Both will in fact transfer you to the download of M3A78 PRO BIOS 1602. What is your current BIOS?