View Full Version : AHCI and SSDs help

03-05-2012, 08:39 PM
So I caved in after the recent RPS article and got an SSD. Thinking it is basically just a faster HDD I got it set up and installed Windows on it and everything works perfectly fine and it is very nice and fast.

Then today I got to the point where I started actually reading about how to set one up properly and I came across AHCI and the fact I should have set my BIOS to use it before I installed Windows.

There are two settings related to AHCI in my BIOS I can see (SATA RAID/AHCI) MODE (currently set to nothing) and ONBOARD SATA/IDE CONTROL DEVICE (currently on IDE)

My questions are: is using AHCI really going to dramatically increase performance/are there any downsides to using it? would I need to change both the previously mentioned settings to AHCI or just RAID/AHCI Mode before reinstalling Windows?

I barely understand what AHCI is (in fact I don't at all) and Google is only confusing me further, so any links to quality articles on the subject would be much appreciated.

03-05-2012, 09:16 PM
all I have to say is yes, it does increase performance.

its the onboard one you want to use as AHCI.

03-05-2012, 09:25 PM
You can switch AHCI mode without re-installing Windows, it just requires some registry tweaking to enable the AHCI driver (see http://support.microsoft.com/kb/922976)

AHCI is very much recommended for SSDs as it enables TRIM, which is a kind of garbage-collection system that will reduce performance loss over time. I'm not 100% certain on how well that would work if you enabled it after the fact though: You may have to do a secure erase anyway to get the full benefit, which would obviously mean re-installing Windows.

As for the BIOS settings, the only reason you would want the SATA controller emulating IDE would be if you had old hardware that requires it. SATA is faster and enables hot-swapping of drives (there may be seperate BIOS settings for that) among other things. IDE is an old, legacy standard.

03-05-2012, 09:46 PM
I just straight up switched the (SATA RAID/AHCI) MODEto AHCI and and I saw a pretty substantial increase in AS SSD Benchmark

I will try a straight up format and reinstall as I have barely got windows up and running yet, it's still installing updates.

Would the setting both settings to their respective AHCI option be the recommended course of action or just the Onboard Control Device?

Thanks, really useful stuff.

03-05-2012, 11:25 PM
I think you would want to set both options to AHCI, unless you have an old IDE optical drive or something.