For AHCI - It's a BIOS setting....download AS SSD benchmark and run it...it'll tell you whether or not you are running in AHCI or IDE. If you're in IDE, you will need to change a setting in your BIOS. HOWEVER...if you installed Windows in IDE mode, and you switch to AHCI without doing the following instructions, your machine will BSOD immediately upon entering Windows. Follow these directions, and you'll be good to go. (I did the same thing, and this worked flawlessly.)
However, check whether you're in AHCI mode first. If you are in IDE, in the upper left of AS-SSD benchmark your drive will show your drive model, then the firmware and then "IDE-BAD" in red. If you are in AHCI mode, it will say "msahci - OK" in green.
Of course your drive info will be different (as will your speeds), but to see what I'm referring to, see here (this is my drive):
If you are in IDE mode, do the following:
Exit all Windows-based programs.
Press [Win] + R or take the RUN option from the start menu.
Now type Regedit there and press Enter Key to open up the Registry Editor Window. (If you receive the User Account Control dialog box, click Continue.)
Locate and then click the following registry sub key:
Code:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\msahci
In the right pane right-click Start in the Name column and then click Modify.
In the Value data box, type 0 [3 is default], and then click OK.
On the File menu, click Exit to close Registry Editor.
Restart your computer
Go to UEFI/BIOS and enable AHCI, Save & Reboot
Another restart will be required to finish the driver installation.