Thanks for this thread, I never thought Xeon could be o/c.
I applied this http://www.overclock.net/t/1577530/guide-how-to-update-the-cpu-microcode-on-the-x99-ami-bios and, the most important part, I used FTP to flash the bios. Nothing else worked : afudos with or without /GAN, afuwin, afuwingui...