According to THIS (edit: wrong link) page on the Asus site, the motherboard will support that CPU starting with the (edit) BIOS. The newest BIOS for that motherboard is listed as 1904. Just make sure the BIOS is updated before installing the new CPU.
Actually the ASUS site does not mention the X6 chips; the X4 PhII 965 is the newest AM3 chip they mention.
So it might work since the newest bios is dated July of this year.
EDIT: There is no electrical or physical reason the X6 chip would not work. It is all about bios. And the newest 1904 bios says it adds support for new CPU; but in the ASUS list of CPU they don't list any new chips that require that new bios. So it is a gamble... but the 1904 bios is probably for the X6 chips. I can't google any confirmation though.