AHCI or IDE?

nheather

Distinguished Member
For a Windows 7 installation with individual disks would you recommend using AHCI?

Four disks in total - 2x SATA HDD, 1x SATA DVDRW and 1x PATA DVD

Would your answer be the same if the install was dual boot Win7 and WinXP?

What if I added a Linux boot aswell?

I've read about AHCI as much as I understand and I gather it gives a slight improvment in performance, noise and energy over IDE.

I'm also aware that XP doesn't have built in AHCI drivers so you need to add these at install.

I'm tempted to go AHCI but if it is going to be a headache then I would be convinced otherwise.

Many thanks for your help.

Nigel
 

Old_Biker_John

Active Member
For a Windows 7 installation with individual disks would you recommend using AHCI?

Four disks in total - 2x SATA HDD, 1x SATA DVDRW and 1x PATA DVD

Would your answer be the same if the install was dual boot Win7 and WinXP? . . . . .

Hi nheather, :)
I have a system with a similar hard drive arrangement to yours (except no PATA DVD) and happily ran a problem-free, dual-boot (Windows 7 trial installation/XP) in AHCI mode until the end of December 2009.

. . . . I've read about AHCI as much as I understand and I gather it gives a slight improvment in performance, noise and energy over IDE. . . . . .

I have read similar descriptions, but couldn't distinguish between the two modes of operation in practice. The only noticeable difference for me was a slight delay to boot-up as the AHCI drivers loaded.

However, another advantage that AHCI gives is the ability to hot-swap SATA drives, allowing them to be used (with suitable SATA and power cables) as huge, fast substitutes for USB drives. :)

. . . . I'm also aware that XP doesn't have built in AHCI drivers so you need to add these at install.

I'm tempted to go AHCI but if it is going to be a headache then I would be convinced otherwise. . . . . .

I used a floppy disk for my driver install, but you can use USB drive or an image burned on a CD instead.

I seem to recall that you can even pre-install them on the formatted hard drive before you commence the Windows install. (I think that method is explained in the readme.txt file supplied with the drivers.)

It was a simple operation for me. I only had to press the key (when prompted at the start of the Windows install) to tell the Windows installer that I wanted to load the drivers during the install.

. . . . What if I added a Linux boot aswell? . . . . .

I added Linux Mint 8 (Helena) to my system. The addition could only be made AFTER the AHCI mode was enabled in the BIOS. Linux Mint was unable to boot from my SATA DVD/RW in LiveCD mode until then

Some of the other Linux distributions that I tried were able to boot in IDE mode, but Linux Mint (a community-enhanced version of Ubuntu) impressed me most, playing all my media straight after install. It is now my main operating system.:thumbsup:

Once the LiveCD was running, the Linux Mint install took about 20 mins.

The AHCI drivers were installed by the Linux installer when it detected the BIOS settings.

I hope this helps you to decide what to do.

John. :)
 

=adrian=

Distinguished Member
If you have Windows 7 already installed and you did not enabled AHCI before installation, you won't be able to enable it now (it won't work), becuase when you install Win 7 without AHCI enabled it thinks that AHCI is unavailable for you and the Windows AHCI drivers won't be installed.

From what I understand, there are 2 ways to cure it if you want to use AHCI.

1. is to reinstall Windows
2. is to edit registry and change one value.

all of that has to be done before enabling AHCI in BIOS (it won't detect any drives).

If you want to registry edit give a go, here is what you need to change:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
change the 'start' entry to have a value of 0
 

imilne

Active Member
If you have Windows 7 already installed and you did not enabled AHCI before installation, you won't be able to enable it now (it won't work), becuase when you install Win 7 without AHCI enabled it thinks that AHCI is unavailable for you and the Windows AHCI drivers won't be installed.

From what I understand, there are 2 ways to cure it if you want to use AHCI.

1. is to reinstall Windows
2. is to edit registry and change one value.

all of that has to be done before enabling AHCI in BIOS (it won't detect any drives).

If you want to registry edit give a go, here is what you need to change:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
change the 'start' entry to have a value of 0

Windows 7 seems quite happy to let you do this. I've just done it today in fact. My drive was installed in IDE mode (a couple of months ago), and today I edited the registry, made that change, rebooted (changed the setting in the Bios), and away it went. Can't notice the slightest difference, but there you go :D

(And I'd recommend making a system restore point beforehand just in case)
 

=adrian=

Distinguished Member
Windows 7 seems quite happy to let you do this. I've just done it today in fact. My drive was installed in IDE mode (a couple of months ago), and today I edited the registry, made that change, rebooted (changed the setting in the Bios), and away it went. Can't notice the slightest difference, but there you go :D

(And I'd recommend making a system restore point beforehand just in case)

I can't see any differnece in performance too :) but it does work :smashin:
 

nheather

Distinguished Member
Thanks - not installed any OS yet - just trying to decide whether to go with AHCI or not.

So those that have gone with AHCI - if you were installing fresh now would you still bother with it.

My dilemma is, there is no real benefit in performance and boot times are slower. But is it best to use it for some reason in the future - I've heard that SSD drives need AHCI, though I have no immediate plans to go SSD.

Cheers,

Nigel
 
Last edited:

Paul Shirley

Active Member
One potentially con, some mboards dont support SMART on AHCI drives. Not a show stopper but worth checking.

Enabling AHCI doesn't automatically enable acceleration features like NCQ (at least under XP), check your disk driver settings. Without them AHCI is no faster than IDE mode. To be fair, even with NCQ enabled I see no improvement, however hard I thrash the drives!
 

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