Well,
The P5B-VM DO Bios was a total bust... The boards are too dissimilar. Eventhough the layouts are almost identical, apparently switching to the Q965 chipset requires a vastly different BIOS.
The good news however is that I have had very promising results with the P5B-V Bios. There are some quirks though:
1) The Intel VGA Bios always posts before the bios POST. Not a big deal
2) The two USB ports below the firewire port do not work
3) The firewire port does not work
4) The LAN is intermittent... If you don't play with LAN settings in the BIOS, and as long as the PXE screen shows before Windows boots, the LAN will show up in Device Manager and work fine. But if you disable PXE or touch the LAN settings, the LAN disappears from the system. This has to do with the fact that the P5B-V hs a Marvell chip and the P5B-VM has a Realtek chip (yes, I changed the module to Realtek).
EDIT: The way the LAN is behaving is that it's ignoring the settings completely in the BIOS. Even if the on-board LAN is set to disabled, it still works. Now the good thing about the Realtek PXE is that if you hit Shift-F10, you can disable the prompt within the PXE settings and it won't try to boot from it each time you start the computer. Now on to when it
doesn't work: If you shut the computer down and turn it back on, the LAN is totally dead. There are no lights on the port and it doesn't show up in Device Manager. If you turn the power supply switch off however, it works again when you turn the computer on. So using a seperate LAN card might be wise. Also take note that the BIOS (The P5B-V BIOS at least) specifies that the second PCI-E port can only run in conjunction with the first one if the second one is configured for 2X. If you force it at 4X, it shuts off the first port.
But the best news is that AHCI works perfectly now! And this BIOS is only 1MB, so there's no need to swap chips.
So it's definitely advantageous to use the modded BIOS if you want to use AHCI. If anyone still requires it (Can't imagine that anyone would though, this board is almost 10 years old now) or has something else to contribute, please reply in this thread.
Thanks
P.S. I am having some trouble with space constraints with this BIOS and inserting new CPU microcodes. It's not that big of a deal... I imagine that if there's a way to remove the Japanese language support module or the Asus EZ Flash, it would free up a lot of space. Again, if you can contribute, please reply to this thread.
EDIT 2 P.P.S: I managed to delete the Japanese language module from the BIOS, and I also removed some errant entries from the CPU Microcode section so I was able to add and replace all the new microcodes without compromising anything. SLIC (Asus) has also been added and tested.
You will have to figure out how to force flash this on your own... I initially used an SPI programmer to flash the P5B-V BIOS and then subsequently used EZ-Flash as was needed.
V MODDED5_SLIC.ROM (Size: 1 MB / Downloads: 14)
If anyone figures out how to modify the BIOS to work properly with the LAN, then it would be much appreciated.
EDIT 3: Unfortunately, the E5430 771 CPU did not work, so it seems that this BIOS will not work with the 771 mod.