ga-990fxa ud3 rev 3 ssd install

I have been having massive headaches with getting an ssd to operate with a gigabyte ga-990fxa ud3 rev 3 motherboard with any other drive fitted.
I was getting really crappy write speeds and had a play with different drivers, cables, different brand ssd’s, uefi, csm, different bios versions and different amd roms etc…
in the end I found out only ports 4 and 5 would allow the ssd to operate correctly with another drive fitted on any channel.
and it was imperative to us the amd sata ahci driver (as opposed to the Microsoft standard driver) or you would get lots of I/O errors on channels 0-3.
some ssd brands you would get the dredded inacessable boot device after install of windows when using channels 0-3
If the ssd was all by its self everything would work at the correct write speed on any channel but if you hot plugged another drive or drives along side the ssd the the write speeds would suddenly jump to less than 20mb per second.
The problem I have is that channels 0-3 are the ports used when in raid mode and 4 and 5 are the ahci/ide/sata only channels.

is there a way I can get the raid/ahci channels to work correctly with an ssd I’m guessing this will require a bios update from the manufacture is there an option rom I could put into my bios with ubu that would fix this issue ?

EDIT by Fernando: Unneeded blank lines removed (to save space)

AFAIK you cannot solve the problem by updating any BIOS module.
My suggestion: Contact the Gigabyte Technical Support and ask for an updated BIOS.