Hey g3p0, Well, I am kinda still trying to figure this out, myself. You Do indeed have the latest BIOS release. I downloaded the .rom zipfile from this page: http://www.asus.com/Motherboards/P5Q_PRO/#support
then extracted and opened with HxD (hex editor) . Searched for your CPUID - I believe that you should be able to delete a KNOWN CPUID and replace with the microcode from an ASUS (as similar as possible) BIOS for your Xeon. You may also have to resize the BIOS .rom or it will give you CRC errors.
If I stumble into any better info or tutorial then I will be sure to come back and post.
Sorry if I have any wrong info in here. FEEL FREE to help out, guys.
EDIT* Okay, I saw a guy on another forum that updated his ASUS BIOS using MMTOOL v3.19 and patched it with the latest Intel microcode. I do happen to have the microcode in this update: www.wholesale-pc.com/microcode-20130906.tgz
... MMTOOL should be easy to find. GOOD LUCK and update us on the progress.