new Win 7 install enable AHCI - Missing operating system

[Silver007A]

I've had some problems with drivers after installing Win 7. Got all that fixed and had a problem getting the pc switched on. Changed WOL settings and it seemed better, but I was getting a checksum error.

I then found this thread-
http://www.sevenforums.com/tutorials/61869-ahci-enable-windows-7-vista.html?ltr=A

I followed instructions, but now after restarting it is a black screen and stuck with-

LOADING OPERATING SYSTEM...
MISSING OPERATING SYSTEM

 

[Silver007A]

By pure chance I hit F12 to see if I could get SAFE MODE but it came up with option to boot from CD / HD etc.

I chose HD and then it gave me options from USB3 or something with a long sequence of numbers. I guessed that was my hard drive. It now started Windows.

I guess that is the boot sequence?

 

[Silver007A]

OK, managed to change that now. Thanks