AHCI or IDE For Mechanical HDD ?

Auld Bint · 24 Jun 2010

Hi,

Is there any real noticable benefit from having a SATA mechanical HDD use AHCI or IDE? Also, if there is any benefit, is it related to the rpm speed that the drive is capable of?

I keep reading conflicting reports on this, some say AHCI is best, others say there is no real difference unless the disk is an SSD.

I am about to do a clean install of Windows 7 on a laptop 5400rpm mechanical HDD so thought I may as well set the mode before proceeding with the install.

Rgds
Auld Bint

Bill2 · 24 Jun 2010

I never noticed any performance difference between the two modes myself. The 2 main advantages of AHCI over IDE though are hot swap and NCQ (if the drive supports NCQ).

Hot swap means you can replace the drive or unplug the device from the computer without rebooting. NCQ (Native Command Queuing) allows drives to accept more than one command at a time and dynamically reorder them for maximum read write efficiency. But NCQ is only a benefit if you are running very intensive disk operations which may not be the case for the average home user.

Practically speaking, use AHCI if your hardware supports it, as it can only enable features of your drive to be accessed. It should be the same or faster than IDE, unless you have a very bad sata controller chipset or something. Also I think some of the first SATA drives supporting some features like NCQ actually did better with them disabled, but I think that is no longer the case.

Yoy can also go through this thread.

Change IDE to AHCI in BIOS - Much better performance

pparks1 · 24 Jun 2010

It's something that I think you need to try and test for yourself.

For example, a while back I went without AHCI because with my mobo, turning on AHCI introduced an 8 second delay at boot that I didn't feel that I could earn back throughout the day of using the computer...so overall I felt slower with AHCI.

However, after a BIOS update....my 8 second delay dropped to about 1.5 seconds and therefore, I felt that the slight edge of AHCI might now be worth it.

Either way, with our without led to barely if any perceivable difference. Benchmarks are sometimes pretty dramatic...but they often don't really quantify real world performance. I base whether or not a change made a difference with a stopwatch and doing some timed averages. That's what matters to me.