AHCI, what does it do and do I need it?

[needmorecarnitine]

Can someone post a good explanation of what it does or a link to a good article?

In my computer I have all SATA drives (no SSD yet) and one external drive (connected to a SATA port) that is usually off. I would like the external drive to be recognized when I turn it on (with the computer already running) instead of having to have it on (the external drive) before starting the computer. I believe that I had it working properly on my Gigabyte S775 motherboard without ever having AHCI enable (could be wrong about that though).

 

[dr.stevil]

http://expertester.wordpress.com/2008/07/24/ahci-vs-ide-–-benchmark-advantage/

This is a pretty good writeup going over the differences between AHCI and IDE interfaces

 

[serpretetsky]

pretty sure you can't hot swap without enabling AHCI. My friend had an external esata drive, but it wouldn't detect unless he had it plugged in on startup. The sata ports were configured in legacy mode.

 

[needmorecarnitine]

OK, I downloaded Intel HECI MB and tried installing iata-enu and get a "does not meet minimum requirements for installing" error.

So I go into bios and select AHCI (vs. IDE) and it crashes multiple times right after it says starting Windows. Go back to IDE and it works fine. How do I install the drivers?

 

[MrGuvernment]

Yes you cant just switch it, you need to d a reinstall / repair install of windows since it uses different drivers.

 

[SicKlown42012]

You need to change a setting in the registry to enable AHIC if you installed the OS in IDE mode. After you do that you can boot up and install the proper drivers.
http://forums.guru3d.com/showthread.php?t=313676

Edit. This is assuming you're running Widnows 7 or Vista, but you didn't state the OS in the OP.

 

[needmorecarnitine]

yeah I guess you need to have it installed before putting on Win 7


Though, here is a method to fix it without doing a new install:

http://www.sevenforums.com/tutorials/61869-ahci-enable-windows-7-vista.html

WAY better than reinstalling!

thanks guys

 

[Red Falcon]

Awesome thread, I never knew how to change from IDE to AHCI within Windows after install, thanks for sharing.

 

[grambo]

On some motherboards the eSATA port(s) are controlled by a 3rd party disk controller (Marvell, JMicron etc). Make sure the BIOS has that set to AHCI if you want hot-swapping. Works fine in Windows 7 for me, all my internal and eSATA drives are AHCI and all are hot-swappable which is really nice as I just turn on the eSATA enclosure for back-up once a week (safer to not have it running 24/7).