GUIDE - Enabling AHCI mode AFTER Windows 7 Installation

[Hilbert Hagedoorn]

A little guide:

I am receiving a lot of emails from users who bought a SSD drive, installed Windows 7 in IDE mode and then realize they need AHCI mode for faster SSD performance. Once you enable that in the BIOS during Windows 7 boot up, the OS will crash.

The common question is, is there a solve for this ?

To answer that question (and I do this safely with all Intel ICHR9/10 chipsets) there is a way to safely enable AHCI mode. Here we go:

1. Startup "Regedit
2. Open HKEY_LOCAL_MACHINE / SYSTEM / CurrentControlset / Services
3. Open msahci
4. In the right field left click on "start" and go to Modify
5. In the value Data field enter "0" and click "ok"
6. exit "Regedit"
7. Reboot Rig and enter BIOS (hold "Delete" key while Booting

In your BIOS select "Integrated Peripherals" and OnChip PATA/SATA Devices. Now change SATA Mode to AHCI from IDE.

You now boot into windows 7, the OS will recognize AHCI and install the devices. Now the system needs one more reboot and voilla .. enjoy the improved SSD performance.

We have not tested this on Vista though.

Update -- we tested and this tweak works in Vista 100% the same.

[DSK]

Ok so would there be any advantage doing this with normal HDDs?

[Mr.Bigtime]

Originally Posted by kylzer

Ok so would there be any advantage doing this with normal HDDs?

yeah seeking for same answer..

[WhiteLightning]

Thanks for the share hilbert

hilbert do you know if this would cause a blue screen on windows boot, when i only changed it in the bios, and not the registry ?

[DSK]

...................am gonna try this i think.

[Hilbert Hagedoorn]

Originally Posted by WhiteLightning

Thanks for the share hilbert

hilbert do you know if this would cause a blue screen on windows boot, when i only changed it in the bios, and not the registry ?

That is correct - if you only change (enable) AHCI in BIOS while the OS was installed with regular SATA then you'll end up with a BSOD during OS bootup.

The method above describes how to divert that.

For normal HDDs do not expect any real perf difference.

AHCI (advanced Host Controller Interface) allows hot-swapping, improves performance allows functions like NCQ, TRIM and so on. It's more flexible and is definitely a notch faster with SSDs seeking high perf in terms of peak performance.

See below, image 1 has SATA install (left img) - Image 2 AHCI (right img).

[zer0_c0ol]

Originally Posted by Hilbert Hagedoorn

That is correct - if you only change (enable) AHCI in BIOS while the OS was installed with regular SATA then you'll end up with a BSOD during OS bootup.

The method above describes how to divert that.

For normal HDDs do not expect any real perf difference.

AHCI (advanced Host Controller Interface) allows hot-swapping, improves performance allows functions like NCQ, TRIM and so on. It's more flexible and is definitely a notch faster with SSDs seeking high perf in terms of peak performance.

See below, image 1 has SATA install (left img) - Image 2 AHCI (right img).

Trim also works on IDE

Quote:
TRIM is non-specific to either SATA controller mode, and will work equally well in both IDE and AHCI-mode. Benchmark Reviews will soon publish a detailed report that illustrates the recovery levels for each SSD controller tested here.

http://******************com/index.ph...&limitstart=12

[Passion Fruit]

Any chance of some before and after benches Kylzer, before you do this?

[DSK]

Originally Posted by Passion Fruit

Any chance of some before and after benches Kylzer, before you do this?

I don't recommend on normal drivers lol

Before


After

[DSK]

yeah sure..

[GenClaymore]

For me it was the other way around kylzer when I install win7 in achi from IDE on my 500Gb seagate barracuda. I notice the different.

[Knox]

I've used ACHI mode with a Toshiba and some Seagates, i usually get a small boost (about 5-8 MB/s) or it stays the same. I've never had it hurt any. But i don't usually see WD drives.

[deltatux]

I notice a speed increase with AHCI on all my drives. On real world transfer speeds instead of benchmark tests.

Plus, having NCQ makes it even better.

deltatux

[mR Yellow]

So who else tested this in regular HDDs?

[TheHunter]

i tried it once, but i keep seeing this AHCI installing driver in dos every time i restarted pc, i had to wait extra 20sec longer..

can i use it if i have dual boot? I have win xp and win7, dont want to mess up WinXP..

[deltatux]

Originally Posted by TheHunter

i tried it once, but i keep seeing this AHCI installing driver in dos every time i restarted pc, i had to wait extra 20sec longer..

can i use it if i have dual boot? I have win xp and win7, dont want to mess up WinXP..

It's not actually DOS, it's part of your BIOS. I guess GIGABYTE's BIOS doesn't include a native implementation of AHCI so it loads either AMD, Intel or NVIDIA's implementation of AHCI during bootup. It actually allows a bit more functionality if you play with it. It's not DOS and you can use it to install any OS like you do normally.

I know ASUS doesn't have this issue as I have both ASUS and GIGABYTE boards in my house.

deltatux

[Norvekh]

Performance depends on your drive controller and drives. In my case enabling AHCI introduces awful stuttering with all of my drives and essentially makes the machine unusable. Disabling it ends the stuttering and gives me higher read/write rates and lower access times.

[Acid81]

Is there any way to do this for XP ?

[Darkiee]

Thank you Hilbert, a ton.

My AS SSD bench score went from 204 up to 303 ^^

[Year]

i've always ran my drives in IDE Mode

tried the AHCI trick, it worked but i'm not seeing any performance increase, i do not raid so i don't need it.

good trick nonetheless that might come in handy someday, worked fine in W7.

[dirthurts]

So I read this post and became more confused than I already was. I am adding an SSD to my computer. Fresh install of Win 7.

Do I somehow set my motherboard to AHCI mode, then Windows 7 will automatically install in this mode?

Where do I find the AHCI mode in my bios? Foxconn A79A-S

Any help would be much appreciated.

[Da{N}ka]

I'm skeptical about NCQ, I like to have it disabled and what I've seen (Please DO correct me if I'm being a total noob) is that with AHCI mode there is no way to disable NCQ.

My setup is as follow :
2x separate Hitachi HDT725032VLA360 320GB SATA : One is C: with Win 7, the other D: with paging file and some temporary download.
1x Corsair CMFSSD-128GBG2D : I gave it the letter S:, it has games installed.
1x Samsung HD103UJ 1TB : This is F: for backup/storage and various file purposes.

Now the controller is in IDE mode (via BIOS of my Asus Rampage Formula) and with HD Tach (Quick bench) I get a Burst Speed result of :
on the 2x Hitachi around 210 MB/s
on the Samsung around 235 MB/s
on the SSD around 247 MB/s

I remember seeing in Win XP and the 780i (yeah I know, different OS different controller) a far better speed with the NCQ disabled, therefore my settings for all HDD in Win 7 are :


And I get a better performance as with the write-cache buffer flushing enabled.

Now, everyone says that SSD should go together with AHCI mode, but still I hate to see performance taken away by NCQ, in my case useless and counterproductive.

Any take on this one ?

(damn i wrote too much..)

[dirthurts]

What is NCQ ?

[Dublin_Gunner]

Originally Posted by Da{N}ka

I'm skeptical about NCQ, I like to have it disabled and what I've seen (Please DO correct me if I'm being a total noob) is that with AHCI mode there is no way to disable NCQ.

You should be able to disable NCQ from within device manager. (right click on your drive(s), go to properties, and its in there iirc).

[Da{N}ka]

Native Command Queuing
http://en.wikipedia.org/wiki/Native_Command_Queuing