ASUS M2R-FVM AGESA upgrade possible?

[C-H]

It's an OEM-Board so I really don't expect anything at this point.
The BIOS has no CPU-Microcode entries, AGESACPU.ROM is all there is as far as I can tell.
Athlon X2 4450e is what I would like this BIOS to support.
Looking at other Boards the support for this CPU was added with AGESA version 3 and up.
This BIOS probably has version 2 since the ROM is half the size of a v3 ROM.

I tried upgrading the ROM to AGESA v.3 using CBROM.
Flashing the modified BIOS works fine, no errors.
CPU is actually recognized correctly, at least in the BIOS.
The Problem is booting into Windows, where I get this bluescreen:
"The BIOS in this system is not fully ACPI compliant."
I tried different cbrom versions as well es different AGESACPU ROMs, it's all the same.

I'm probably doing something wrong, or maybe it can't even be done.
In any case I thought I'd ask.

Link to the "latest" BIOS

Any hints and or help with this would be greatly appreciated.