Inspiron 620 SSD upgrade no longer supporting AHCI with Windows 10

Hello all,

I had installed a Crucial CT256MX100 SSD when using Windows 7 without properly checking the settings for AHCI and TRIM. This seemed to be working fine and providing a very high data transfer rate, however on upgrading to Windows 10 (overnight... :/ ) there was a significant slowdown (20 second power on to 4 minutes). Having looked around for a way to rectify this, I was unable to locate the option for AHCI within the BIOS for my Inspiron 620. It states within the system manual that it is an option, any idea on how to enable it? Reinstall the OS?

To anyone who can offer constructive help, thanks in advance!