Win 7 wont load in AHCI mode? Is this because I installed in IDE mode?

BoroRob_UK · 19 Dec 2009 at 01:02

???

I installed Win 7 in IDE mode.. now switching to AHCI (which ive been told is better) Windows gets to 'Starting Windows'... then reboots.

Any ideas?

Ross1234 · 19 Dec 2009 at 01:03

What gave you the impression AHCI is better?

BoroRob_UK · 19 Dec 2009 at 01:16

My motherboard manual states, "The ACHI allows the onboard storage driver to enable advanced Serial ATA features that increase storage performance on random workloads by allowing the drive to internally optimize the order of commands". ?

Ross1234 · 19 Dec 2009 at 01:16

In real life benchmarks it is slightly quicker in some things (3% maybe) and a good bit slower at reading files.

BoroRob_UK · 19 Dec 2009 at 01:18

So IDE mode is faster than ACHI at reading? why cant I boot in it? Do i have to install from ACHI mode first?

Ross1234 · 19 Dec 2009 at 01:20

"I am not 100% sure about W7, but in Vista, the way to enable AHCI after installation is -
- Set BIOS back to IDE
- Start Windows
- Run Registry Editor
- Go to HKLM\System\CurrentControlSet\Services\Msahci
- Change the "Start" value to 0
- Reboot and go to BIOS immediately
- Set BIOS to AHCI

The next time you load Windows, it will auto-detect the AHCI."

BoroRob_UK · 19 Dec 2009 at 01:24

Anyone know if you have to do something similar for Win7? Also, what is best, IDE or AHCI? I seen a lot of people goin on about AHCI...?

Ross1234 · 19 Dec 2009 at 01:31

I have heard you do the same for 7. It makes it load the AHCI driver the next time you start up.

BoroRob_UK · 19 Dec 2009 at 01:42

Ross1234 said:
I have heard you do the same for 7. It makes it load the AHCI driver the next time you start up.

Yeah. Reg key is exactly the same... Can't notice any difference yet tbh tho'

Ross1234 · 19 Dec 2009 at 01:44

So its working in AHCI?

BoroRob_UK · 19 Dec 2009 at 01:47

dazzerd · 20 Dec 2009 at 22:36

Hmm not sure why you gotta do all that. The problem with selecting ahci from my experience is that optical drives become flakey if you use it on an ahci channel. In fact when I first got 7 I got up to the install section and it just hung.

Eventually I just dropped the internal optical and used external and it installed everything automatically and is fine to this day.

If you have two disk contollers on your mobo you could prolly keep the optical on ide but the hard drives on ahci and it should be fine.

Doesnt really add much to be honest performance wise. I need it though as I do hot swap drives quite often so it helps.

ejr22 · 20 Dec 2009 at 23:53

Ross1234 said:
What gave you the impression AHCI is better?

The advantage of AHCI, in this case, would be that automatic TRIM will work with his Intel SSD (assuming he has the latest firmware). I don't think it works in IDE or RAID mode.

ChileanLlama · 20 Dec 2009 at 23:55

No, TRIM works in IDE. The benefits of AHCI are that you'll get a bit more performance out of an SSD as it will take advantage of NCQ.

ChileanLlama · 21 Dec 2009 at 00:01

dazzerd said:
Hmm not sure why you gotta do all that...

Because if you install Windows in IDE mode, the setup loads the IDE drivers to allow it to boot, it doesn't install AHCI drivers. If you want to change to AHCI after setup, you need to force Windows to make available the AHCI drivers - if not and it only has IDE drivers available but BIOS set to AHCI windows will crash/BSOD during boot.

The workaround Ross1234 provided means you don't need to reinstall Windows when you change from IDE to AHCI.

AbsenceJam · 21 Dec 2009 at 05:18

ChileanLlama said:
No, TRIM works in IDE. The benefits of AHCI are that you'll get a bit more performance out of an SSD as it will take advantage of NCQ.

NCQ is slower for single-user.