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Can I switch from AHCI to IDE without re-format/re-install?

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May 26, 2011 3:52:24 PM

One question I have not seen answered is: Can I switch FROM the AHCI mode to IDE mode, WITHOUT having to re-format/re-install the O/S?

I know that I have to re-format/re-install if I switch [from] IDE to AHCI, but I need to know the opposite of that.

And I don't want answers like, "Well, you SHOULD be able to." I want real-world experience, where someone (MULTIPLE someones preferably) say, "Oh, yes, I did that exact thing without a problem" or, "Oh, no - you can't do that - you will have to reformat.... "

Thanks!
May 26, 2011 8:08:36 PM

The reason you were told that had to re-install was because Windows disables drivers it does not require. Look at

http://support.microsoft.com/kb/922976

for details. There it tells you how to avoid reinstalling at all by enabling the AHCI drivers prior to switching, but also says that the IDE drivers are Pciide.sys. Check what the registry values are for this, and make the appropriate modification.

BUT I've not done this myself as I've not had a need to go back to an IDE drive from an AHCI one...
a c 277 G Storage
May 26, 2011 9:01:09 PM

In the absolute worst case (and I mean this, you should be able to do a registry twiddle instead), you will have to boot up your OS disk and do a repair install. What version of Windoze?

And you don't need to re-format / re-install to change mode from IDE to AHCI. In Win7 you can do a registry twiddle, then reboot. In earlier versions, a repair install does the job. I've done it in XP. Both ways. Oh, yes, I did that exact thing without a problem. (happy?)

Out of curiousity, why do you have to do this? I'm not challenging you, it's just the first time I've seen someone want to go in that direction.
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May 26, 2011 9:10:55 PM
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In XP and 7, I've never had a problem switching from AHCI to IDE after installing Windows. Switching from IDE to AHCI though you have to reinstall or do the registry edit. That's my personal experience.
a c 415 G Storage
May 26, 2011 9:46:52 PM

I've posted these instructions for other people who say it worked for them:

1) Run the Registry Editor (regedit.exe)
2) Navigate to Registry Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
3) Set the "Start" value to 0 (zero)
4) Navigate to Registry Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Pciide
5) Set the "Start" value to 0 (zero)
6) Shut down
7) Start up again, but before Windows boots go into the BIOS configuration screens and change the disk mode to "AHCI". Save the new BIOS configuration and restart so that Windows boots.

When Windows starts, it will detect the change, load new disk drivers, and do one more reboot to start up with them.
May 27, 2011 3:17:21 AM

WyomingKnott said:
In the absolute worst case (and I mean this, you should be able to do a registry twiddle instead), you will have to boot up your OS disk and do a repair install. What version of Windoze?

And you don't need to re-format / re-install to change mode from IDE to AHCI. In Win7 you can do a registry twiddle, then reboot. In earlier versions, a repair install does the job. I've done it in XP. Both ways. Oh, yes, I did that exact thing without a problem. (happy?)

Out of curiousity, why do you have to do this? I'm not challenging you, it's just the first time I've seen someone want to go in that direction.


Yes, that made me VERY happy. LOL.

But, can I say HUH? I thought if I am going AHCI to IDE, I should not have to do ANY added things, like install/repair?

As for 'why,' it shouldn't matter, but I will tell you anyway: The client does not need or utilize that added speed, nor the added features. They may save a Word or Excel doc every few hours. Additionally, it is my understanding that, if you had to rebuild, and you are in AHCI mode, then you have to hit F6 and load some added drivers? I am in Vista, so i'm not sure if that F6 step would be needed, since Vista supports ACHI natively. Don't need hotswap; don't need RAID; don't need no credit card to ride this train... AND, with various threads I've read, most people state that there is NOT that much [noticeable] difference in the AHCI/300 vs. the IDE/150 speeds.

AND, the REAL 'real' reason i wanted to switch from AHCI to the more standard, no-driver-needed, tried and true IDE mode, was because I was having odd "hangup" issues which sort of indicated maybe something in the area of the disks drives; firmware, AHCI, drive going bad, etc. Well, upon running Dell diags, the return code indicated the HDD was *TOAST*... so, as of NOW, I do NOT have any need to change modes - i.e., previously, I was going to eliminate AHCI as a possible culprit.

Thanks for all the feedback!
a c 415 G Storage
May 27, 2011 5:33:33 AM

jman_26 said:
... i wanted to switch from AHCI to the more standard, no-driver-needed, tried and true IDE mode...
AHCI is a very well established, robust protocol that shouldn't be causing you any problems. IDE compatibility mode is only there for ancient operating systems that don't have the smarts to deal with modern devices. There really isn't any good reason to SATA ports in IDE compatibility mode if the OS supports AHCI.
May 27, 2011 5:50:47 PM

sminlal said:
I've posted these instructions for other people who say it worked for them:

1) Run the Registry Editor (regedit.exe)
2) Navigate to Registry Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
3) Set the "Start" value to 0 (zero)
4) Navigate to Registry Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Pciide
5) Set the "Start" value to 0 (zero)
6) Shut down
7) Start up again, but before Windows boots go into the BIOS configuration screens and change the disk mode to "AHCI". Save the new BIOS configuration and restart so that Windows boots.

When Windows starts, it will detect the change, load new disk drivers, and do one more reboot to start up with them.


Okay, that actually DID solve my issue with migration from IDE to AHCI! (Got BSOD during Win7 boot if switched to AHCI in BIOS before). It isn't faster (still takes like 30 seconds to boot), but at least it works =) Thanks a lot!
June 3, 2011 1:30:52 PM

sminlal said:
AHCI is a very well established, robust protocol that shouldn't be causing you any problems. IDE compatibility mode is only there for ancient operating systems that don't have the smarts to deal with modern devices. There really isn't any good reason to SATA ports in IDE compatibility mode if the OS supports AHCI.


Excuse me, but there is ALWAYS a good reason - and I indicated my reason: TROUBLESHOOTING.

Jeez! Sure, it "shouldn't be causing" any problems but, to elimiate it as a possibility, it makes sense.
Additionally, as I pointed out, some articles indicated a need for DRIVERS - which I may or may not have; and nobody could really answer if any F6 additional drivers were needed.

So, please don't assume to know what is best for someone. Sometimes we need IDE because that's the longest-standing MOST compatible standard - AHCI still has a few compatibility issues - mostly minor, I'm sure; and older devices and older architectures as well as newer architectures, all play very well with just the standard IDE.

So, again, it is a troubleshooting and 'personal preference' issue - personally, I deal with a lot of older systems, due to helping out churches, non-profits, homeless, etc. - so IDE is very prevalent.
June 3, 2011 1:32:39 PM

amk-aka-Phantom said:
Okay, that actually DID solve my issue with migration from IDE to AHCI! (Got BSOD during Win7 boot if switched to AHCI in BIOS before). It isn't faster (still takes like 30 seconds to boot), but at least it works =) Thanks a lot!


And THIS comment has NOTHING (*Z-E-R-O*) to do with MY question!

I asked exactly THE OPPOSITE. Please *READ* the question, before commenting!

I wanted to know about switching F-R-O-M AHCI to IDE.

Thanks.
June 3, 2011 1:34:00 PM

Best answer selected by jman_26.
November 4, 2011 11:17:22 PM

First: To answer the question "Why IDE?" (as it is an ancient interface akin to MFM and RLL. . . :kaola:  )

All aplications are NOT created equal - I have a copy of Apricorn's EZ Gig II drive clone/image software that I use to make "cold" system bare-metal backups. I use it because (IMHO) it's a Hot Smokin' Weapon. Even though the CD uses some flavor of Linux, it does NOT support AHCI. Ergo, I have to switch to IDE to run these backups.

(Though I am REALLY TEMPTED to reverse-engineer the disk and update it to a more modern kernel, or include the kernel module for AHCI to eliminate this BOOOOGUS Bull-S**t. :fou:  )

I am thinking really hard about switching *TO* AHCI to enable my eSATA's hot-swap feature.

In any event, everyone has (what they believe to be) perfectly valid reasons for using one interface or another, one system or another, one OS or another, or even using a Mac! :lol:  So, let's play nice in the sandbox everyone. OK?

What say ye?

Jim (JR)
November 5, 2011 1:52:54 AM

jharris1993 said:
First: To answer the question "Why IDE?" (as it is an ancient interface akin to MFM and RLL. . . :kaola:  )

All aplications are NOT created equal - I have a copy of Apricorn's EZ Gig II drive clone/image software that I use to make "cold" system bare-metal backups. I use it because (IMHO) it's a Hot Smokin' Weapon. Even though the CD uses some flavor of Linux, it does NOT support AHCI. Ergo, I have to switch to IDE to run these backups.

(Though I am REALLY TEMPTED to reverse-engineer the disk and update it to a more modern kernel, or include the kernel module for AHCI to eliminate this BOOOOGUS Bull-S**t. :fou:  )

I am thinking really hard about switching *TO* AHCI to enable my eSATA's hot-swap feature.

In any event, everyone has (what they believe to be) perfectly valid reasons for using one interface or another, one system or another, one OS or another, or even using a Mac! :lol:  So, let's play nice in the sandbox everyone. OK?

What say ye?

Jim (JR)


Dude, this thread is 5 months old... Lol, nobody cares any longer.
February 21, 2012 12:16:52 PM

arson94 said:
Dude, this thread is 5 months old... Lol, nobody cares any longer.



Hmm... I don`t thing so...

I prepared implenetation img for Dell Latitud E5420 in Virtual machine... so I do everthing as well, install necessary programs and so on... img works fine, after I try to implement this img on Dell Optiplex 390 ... bios got only one options SATA drives ATA mode ... no AHCI :( 

... my question is - How can I change AHCI mode to IDE mode in Win 7 ?
August 12, 2012 4:21:13 PM

sminlal said:
AHCI is a very well established, robust protocol that shouldn't be causing you any problems. IDE compatibility mode is only there for ancient operating systems that don't have the smarts to deal with modern devices. There really isn't any good reason to SATA ports in IDE compatibility mode if the OS supports AHCI.


Trust me, there are several 'good reseasons'. But anyway, I wanted to point out that your "Step 4" differs from what Microsoft's "Step 4" fix states. I'm referring to the very last word in the second registry line where you listed: "\Pciide" and MS says to choose the line with this as the last word: "\IastorV".

Why did you choose the 'Pciide' one? I mean, yours makes sense but as I said MS says to do it differently and I just want to get clear understanding of your fix.

I realized this can be an old topic and has run its course but if you get a moment to clarify I would appreciate it. Otherwise I would have to choose MS's fix because of obvious reasons.
Thanks, Rich
April 25, 2013 11:38:41 PM

I can give you one very good reason for going "AHCI to IDE". WHAT IF you had a dual boot set up? (W7/XP) and
WHAT IF you had a BOIS that permitted IDE either on ONLY ports 4 & 5 (of 6), OR on all 6. IN OTHER WORDS you
can set 0 - 3 to IDE, AHCI or RAID, but 4 -5 can only be RAID or IDE. Switching 0 - 3 to IDE makes vanish the
setting for ports 4 - 5 and sets all six to IDE. OK? NOW WHAT IF when booting to XP you'd like to have access to
more than just 2 of the six sata-III ports? For example both ROM drives and perhaps a second (non-SSD) data drive?
What really pissed me off was the fact that I couldn't set 0-3 to IDE and 4-5 to AHCI. ONLY the other way around.
April 29, 2013 9:18:18 AM

arson94 said:

Dude, this thread is 5 months old... Lol, nobody cares any longer.


Arson94,
If I had to pick the one thing that torques me the absolute most in thread postings it is comments like this.

First: Since people are searching for, and finding, this forum posting, it is obviously still of interest for SOMEONE.

Second: Blowing off someone's answer or contribution simply because YOU think the thread is dated discourages others, who may depend on the help offered here, from posting their issues and receiving the answers they deserve.

==================================

To answer the earlier question:

Quote:

I wanted to point out that your "Step 4" differs from what Microsoft's "Step 4" fix states. I'm referring to the very last word in the second registry line where you listed: "\Pciide" and MS says to choose the line with this as the last word: "\IastorV".

Why did you choose the 'Pciide' one? I mean, yours makes sense but as I said MS says to do it differently and I just want to get clear understanding of your fix.


I don't know about the earlier comments, but in the text of the fix *I* read, and in the registry entries of all the operating systems *I* have patched, it has always specified the "Pciide" key.

Hopefully that helps.

What say ye?

Jim (JR)
April 29, 2013 10:19:55 AM

jharris1993 said:
arson94 said:

Dude, this thread is 5 months old... Lol, nobody cares any longer.


Arson94,
If I had to pick the one thing that torques me the absolute most in thread postings it is comments like this.

First: Since people are searching for, and finding, this forum posting, it is obviously still of interest for SOMEONE.

Second: Blowing off someone's answer or contribution simply because YOU think the thread is dated discourages others, who may depend on the help offered here, from posting their issues and receiving the answers they deserve.

==================================

To answer the earlier question:

Quote:

I wanted to point out that your "Step 4" differs from what Microsoft's "Step 4" fix states. I'm referring to the very last word in the second registry line where you listed: "\Pciide" and MS says to choose the line with this as the last word: "\IastorV".

Why did you choose the 'Pciide' one? I mean, yours makes sense but as I said MS says to do it differently and I just want to get clear understanding of your fix.


I don't know about the earlier comments, but in the text of the fix *I* read, and in the registry entries of all the operating systems *I* have patched, it has always specified the "Pciide" key.

Hopefully that helps.

What say ye?

Jim (JR)



Well, I might have been drunk when I made that post so I'll apologize for that. However, my comment was a year and a half ago and this thread was marked as solved 5 months before that by the OP. It has always been my understanding that the etiquette in your situation would been to create your own thread since you were asking for advice instead of reviving a solved thread that was 5 months old.

Again, my reply was not in the best manner and I admit that. In my defense, there's a 105% chance I was under the influence of a Miller and/or a Coors product when I posted that reply as I have just verified that November 5, 2011 was a saturday. And by under the influence I mean probably at least a 30-pack since I made that comment before 9AM on a Saturday morning. There's only one reason I'd be awake before 9AM on a Saturday morning and that's because I'm still drinking from Friday night. Obviously I don't remember any of this and I rarely do when a keg is involved. My bad.
April 29, 2013 11:30:15 AM

arson94 said:

Again, my reply was not in the best manner and I admit that. In my defense, there's a 105% chance I was under the influence of a Miller and/or a Coors product when I posted that reply as I have just verified that November 5, 2011 was a saturday. And by under the influence I mean probably at least a 30-pack since I made that comment before 9AM on a Saturday morning. There's only one reason I'd be awake before 9AM on a Saturday morning and that's because I'm still drinking from Friday night. Obviously I don't remember any of this and I rarely do when a keg is involved. My bad.


That happens to all of us.

I've had to dig out my recipes for humble pie and crow on a few occasions myself as Percocet - a fairly strong pain killer - can torque your head into a pretzel too, and sometimes I am not exactly at my diplomatic best. ( :pt1cable:  )

I also understand the idea of not resurrecting old threads - however, (at least IMHO), if the thread is still generating significant hits, this is the place to put the comments, not some new thread that may not be found, 'eh?

I have my own blog, qatectips.com where some of my postings that are several years old still generate significant numbers of hits, comments, and questions. Rather than tell them to "bloody 'naff off!" I try to be as patient as possible, answer their questions, and try to be as helpful as possible.

Jim (JR)
November 20, 2013 9:31:40 AM

jharris1993 said:
arson94 said:

Dude, this thread is 5 months old... Lol, nobody cares any longer.


Arson94,
If I had to pick the one thing that torques me the absolute most in thread postings it is comments like this.

First: Since people are searching for, and finding, this forum posting, it is obviously still of interest for SOMEONE.

Second: Blowing off someone's answer or contribution simply because YOU think the thread is dated discourages others, who may depend on the help offered here, from posting their issues and receiving the answers they deserve.

==================================

To answer the earlier question:

Quote:

I wanted to point out that your "Step 4" differs from what Microsoft's "Step 4" fix states. I'm referring to the very last word in the second registry line where you listed: "\Pciide" and MS says to choose the line with this as the last word: "\IastorV".

Why did you choose the 'Pciide' one? I mean, yours makes sense but as I said MS says to do it differently and I just want to get clear understanding of your fix.


I don't know about the earlier comments, but in the text of the fix *I* read, and in the registry entries of all the operating systems *I* have patched, it has always specified the "Pciide" key.

Hopefully that helps.

What say ye?

Jim (JR)


Thank you Sir! It's a VERY LATE "thank you" but genuinely meant all the same.

I just happened by the website and realized that I had never received notifictaion to a reply on this so I was surprised when I saw a note that alerted me a response was made!
Rich ;) 

!