Have you tried installing BIOS 73 via the BIOS Recovery process?
For information on the BIOS Update process, consult Intel Desktop Boards BIOS Update Instructions and, for the BIOS Recovery process, consult Intel Desktop Boards Recovery BIOS Update Instructions.
To help you better, here are my step-by-step instructions for BIOS Recovery:
Hope this helps,
Glad I could help. Fact is, it's the only remedy that we have left in the arsenal for these boards. If you cannot get to the latest BIOS using the BIOS Recovery method, you're not going to get there. No one thought to ensure that the specific intermediate BIOS releases necessary would be available someplace. I kept a backup of only the latest BIO files for each board but I didn't even remember to save a copy of the release notes. In my defence, I just didn't have the time to save everything. Regardless of the time available between announcement and removal (and, I am embarrassed to say, I heard about the decision to remove everything long before the actual announcement), life gets in the way and you always end up in a panic doing it at the last minute.
[Aside: It is true that, in some cases, you might find some of these intermediate BIOS releases on one of the third-party BIOS/Driver download sites. The problem is that I do not trust these sites. They can proclaim their integrity all they want; in this day and age, considering all of the focused (read: state-protected and state-funded) hacking teams that exist, I simply don't see anything that would make me want to trust these kinds of sites. Keeping my PCs clean is tough enough without taking these kinds of chances.]