I am bumping this thread because I am running into a similar issue I believe.
I have the same OEM mobo and was looking to upgrade my Titan X Pascal to a 2080ti RTX card. However, it hangs at the Bios loading screen, beeps once, and then just fails to restart.
This is what my current BIOS version is:
ASROCK H67DE L1.25Z
Anyone know if flashing the bios will allow support for the RTX card? Also, if anyone has a guide on how to safely flash this mobos bios...that would be greatly appreciated. That is a step I have never had to take before.