Solved AHCI Mode After Windows 7 Installation MBR 3 MBR1 Error

[WessexWyvern]

Hi, I've just installed an SSD drive (Samsung EVO 840) and set it up with Win 7 by cloning the previous drive. I'd like to switch from IDE to ACHI mode and I followed the instructions at the foot of this post prior to switching the "On Chip SATA type" in the BIOS from IDE to ACHI and have had partial success*, although I get the following error:

MBR Error 3
MBR Error1
Press any key to boot from floppy...

(there is no floppy drive installed in my machine)

*If I restart the machine, open up the boot menu and select "a first boot device" as

"+Hard Disk" / "SCSI-1ort :2-Samsung ssd 840"

Windows 7 boots up fine. However if I restart it, I get the same error and have to manually select a boot device again.

If I switch back to IDE mode in the bios the problem goes away but then I get then get a reduced SSD performance. Can anyone help me fix this?

Edit: I had a second data HDD connected when I installed the ssd if that makes a difference?
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Instructions: Exit all Windows-based programs.
Click Start, type regedit in the Start Search box, and then press ENTER.
If you receive the User Account Control dialog box, click Continue.
Locate and then click one of the following registry subkeys:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\IastorV
In the pane on the right side, right-click Start in the Name column, and then click Modify.
In the Value data box, type 0, and then click OK.
On the File menu, click Exit to close Registry Editor.

 

[WessexWyvern]

I've changed the boot order in the bios to ensure the ssd is number 1 on the list. This has resolved it.