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IDE vs AHCI

N

Nismo

[H]ard|Gawd
Joined
Mar 10, 2000
Messages
1,413
What have been your findings on this situation? I've read countless articles and need to decide soon. I've got a new system built with a single Raptor, soon to be a SATA3 SSD when they are availiable. Windows 7 x64.

Are there any negative effects of enabling this feature?

Do you need it enabled for external eSATA devices to be hot swapable?
 
i am not sure on windows 7 but i know on windows xp if you enable ahci mode after os was isntalled on ide you have to reinstall windows.
 
AHCI is supposed to give a performance increase, however with a Raptor, I doubt you will see any gain. SSD you will more than likely want to use AHCI.

Once bit of caution is that sometimes optical drives to not like to be run on ports that are set to AHCI. Most of the issues I've seen are that the BIOS will no longer detect the optical drive when the SATA ports are switched to AHCI, or if the BIOS does, the optical drives will still not be usable to boot to, or inside an OS.
*This issue is becoming less frequent and new optical drives will probably not have any issues. Still worth mentioning just in case.
 
You should use AHCI unless you have an operating system older than 10 years (like Windows XP). IDE emulation mode will hide features like NCQ and Hot-Plug.
 
I just got an intel x25-m g2 ssd two days ago and coupled that with windows 7, at first I had my system running on ide mode instead of ahci. I ran the AS SSD benchmark and compared my results to those of reviews and people that had benchmarked their drives and noticed that my results were considerably lower. I then switched to ahci and saw a pretty big increase in the numbers i got from AS SSD after the switch. Applying that to the real world, my SSD read speeds increased a little.
 
The big increase would be in multiqueue random IOps, as Intel drives use NCQ as command buffering; able to process multiple I/O in parallel. The result is up to 100MB/s on read IOps from an Intel drive (64 queued I/O's).
 
Do you need it enabled for external eSATA devices to be hot swapable?
Click to expand...

Yes, the controller for your eSATA port must have AHCI enabled for hotswap to work.
 
Totally OT but you a Nissan guy? For those who don't know Nismo = Nissan motorsports.
 
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