Well, the plot thickens!! The original claim stands that >2tb on marvell raid is no longer possible with bios F11 or F12a
The reason why I was getting inconsistent results with version F7, is to with the way bios looks for bootable drives when the marvell chip is set to raid.
Normally, when you have a fresh drive/s and you start the computer with a bootable windows dvd in the drive, after the bios has finished post it will automatically boot the dvd drive. You will NOT see the message "Press any key to boot cd/dvd", because bios can see that there are no other bootable devices connected.
However, when the drives are connected to the marvell chip and are configured to raid, for some reason bios thinks there is an alternative boot drive besides the dvd and you do see the message "Press any key to boot cd/dvd".
If you ignore that messsage, there is a momentary flash on the screen with text on the left top quoting the bios date and version and on the right top 'press del or f2 to enter setup"
If you allow this to happen, you will find that you cannot partition more than 2tb of the raid volume.
If you DO press a key when you see the boot message and not allow the flash on the screen to happen, you can partition the whole raid volume as a single partition [with the usual small system partitons of course]
However, this is only possible with bios F7, it is not possible to partiton >2tb on the marvell chip with F11 or F12a.
No matter what I do, with F12a I always get a message that windows cannot install to this volume, when you click details it says "The computers hardware may not support booting to this disk, make sure the device is enabled in bios".
At which bios version this was broken, I don't know. All I know is that F7 works [with attention to boot message] and F11 or F12a don't work
I think this can be elevated to bug status.