Foolishly, I installed Windows 7 with my new SSD set to IDE. I would like to change it to AHCI. I have done this before, with a different motherboard.

What happens:

• I set the controller to AHCI in the BIOS; I also check correct boot order
• On boot, I get the 'BOOTMGR not found' error
• I use the Windows Recovery Console on the DVD
• Diskpart etc can see the disks, and bootrec claims to have rewritten the MBR/bootloader
• I reboot, same problem
• Recovery Console again and it detects a problem, fixes, reboots
• Recovery Console again and it detects the OS, and a problem - fixes, reboots
• I ignore the 'press any key to boot from DVD' prompt
• Windows boots fine
• I restart without the DVD and I'm back to square one

That optional 'press a key to boot from DVD' stage is something that the recovery process introduces - normally you have to choose to boot to the DVD at the BIOS stage. You also see this when installing Windows. I suspect that whatever temporary state that is is compatible with AHCI - but not the standard it returns to.

I have done the msahci/iaStorV registry hacks to no avail (this worked with the previous board). I can put it back to IDE where normal service is resumed. The board is an Asus M5A99X, the southbridge is AMD SB950, and this is Windows 7 x64. I would quite like not to have to reinstall it again.

Any ideas as to what I can do as a permanent fix?