Improve SATA hard disk performance (Convert from IDE to AHCI)

Published in Windows 7 Performance Tweaks by Steve Sinchak with 282,030 views

Every hard drive in a modern computer is connected to the system through a storage controller. This controller typically can communicate with the hard drive via a number of different interface protocols. For maximum compatibility many computers are configured in the BIOS to use the older IDE interface protocol to communicate with modern SATA hard drives. This setting is acceptable for the average computer user but IDE lacks support for new technologies such as native command queuing (NCQ) and hot-plugging hard drives (add or remove drives without restarting the computers).

Intel invented a new storage controller interface known as AHCI (Advanced Host Controller Interface) that supports these new technologies with modern SATA hard drives. If you have a hard drive that supports NCQ, it is worth a try to see if your disk performance improves with your workload.

The main problem preventing users from changing the storage interface protocol from IDE to AHCI in the past has been blue screens that could only be cured by undoing the BIOS change or reinstalling Windows. The cause of the problem is the mass storage driver installed when Windows was first setup. Since IDE was enabled at install only the IDE storage driver was configured in Windows. With the AHCI driver missing, Windows cannot read from the hard drive and throws a BSOD with error code 0x0000005B.

Now there is an easy solution that will allow you to switch between IDE and AHCI in the bios and Windows will boot without any problems. The key is to enable the AHCI driver in Windows before you make the setting change in the BIOS.

For most users this will work:

  1. Open Registry Editor and navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\msahci.
  2. Right click on the Start registry DWORD and select Modify.

  3. Set the value to 0 and click OK.

  4. Now the Start setting should be set to 0.

  5. Reboot and enable the AHCI setting in your BIOS.

If you are using a RAID adapter or other interface try the following:

  1. Open up Registry Editor and naviage to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStorV OR HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\iaStor.
  2. Repeat the steps above.

Not all users will see a major performance improvement with AHCI and a SATA hard drive but NCQ can be very helpful under the right workload. Post your experience and setup in the comments below.

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I'm running XP SP3 and searched the whole registry for this and found nothing.
Posted by Woody on 4 years ago

Posted by Quake on 4 years ago

Thanks! Works like a charm on our workstations with Windows 7 Pro :-)
Best Regards
Posted by John Nielsen, Nielco IT on 4 years ago

Well,it works!!!
I always wanted to do this,after i installed my Win7 64 Bit Ultimate a year ago,but it was installed automatically SATA on IDE.
I have ASUS M4N82 Deluxe board and i changed everything like you write above and it works fine and after i reinstalled nforce SATA-IDE driver again,system shows under IDE the new nforce SATA and all the CD-DVD drives are now Scsi and they all work fine.
The only thing is that,the system start-up needs maybe 3-5 seconds more but everything works much faster,copying is faster..
Thanks a lot for the TIP.
Posted by Kurt on 4 years ago

So you can do this if your using a RAID 0 Array?
Posted by Chisel on 4 years ago

Seems to be a little bit faster using windows 7 x64. Do a backup of the registry before. Just in case.
Posted by Dan on 3 years ago

Search my Win 7 Ultimate x64 registry but no sign of the mentioned registry key, now what?
Posted by Chris on 3 years ago

Posted by Rex Holes on 3 years ago

Does this work with SSD's?
Posted by J Lear on 3 years ago

Running Win7 ultimate 64bit and it worked like a champ. thanks
Posted by Geo on 3 years ago

It works with SSDs that support NCQ.
Posted by Steve on 3 years ago

Can Acer AMD computers do this? it isn't an intel, but for the hard drive, I'm not sure what it could be...
Posted by Ari on 3 years ago


Thanks. I needed to change to AHCI for eSATA support on my Dell E6510 and everwhere I looked people were saying to reinstall. Thanks to you I made the single regedit and it worked. Thanks again.
Posted by Robert on 3 years ago

at first this seemed to speed things up, but then i found that it bogged my whole computer down for some reason. file transfer, folder browsing, refreshing. switched back to ata and now everything is fine again?
Posted by Helios on 3 years ago

Yes this worked a treat, HotSwap seems alot more stable however Disk Access times have significantly decreased i know its not the end of the world but i used to like to see my 7.9 in my Windows Experience Index its now 7.4 as the disk access times dropped .5 points.
Posted by Darrell on 3 years ago

Okay i made the registry change and then rebooted and made the bios change to AHCI , but now when i reboot it says no boot device found, after initializing the ahci app it searches for ahci drives? what am i doing wrong? win7 pro x64 4 sata2 hdisks.
Posted by GigaByte69 on 3 years ago

i had been trying to get it worked out for 2months. I did have to make sure i re set my boot order since i had my boot drive in 1 instead of 0 . i have a CoolerMaster II advance with the top sata slot for hdd to hot swap and could never get it together. I have a gigabyte 890FXA ud5 board and couldnt figure how to make it work without reinstalling the OS and i did not want to do that.
Posted by johnniedoo on 3 years ago

I have a gigabyte ga 890FXA UD5 board and always got the blue screen even though the drivers were installed. I did this tweak and finally, it works for a couple of drives. i have 4 total, 3 of them are identical samsung spinpoints in consecutive sata plugs in the board and the 4th one is in an external esata plug from the back.
2 show as scsi and 2 in the ahci, i get a prompt at boot to press any key to continue , though i do not have to press any key, it just boots the same way regardless. it just ids the one external hdd and one samsung. hard to tell one from the other since they are all the exact same numbers. I have no idea if this is typical or not, i do not know if a raid array is set up somehow that i am not consciously trying to do. 2 drives are listed as ncq for sure, i had a similar problem that poster GigaByte69 listed and almost the same drives i have win7 x 64 3sata II internals and the one external sata II in an esata plug. i do not notice any real performance differences, which is good in a way because nothing got messed up. i may have slowed down some disc to disc copy speeds though. i have tested the hdds and all are good run just above room temps in the box the hottest one is the external, i used crystal disc disk mark or disk info to check them as well as pc wiz
Posted by johnniedoo on 3 years ago

Does anyone know how to reverse this on a Dell M90???
It worked so well on my M6400 that I just did it on the M90, but it now it won't boot...
Posted by Tomas on 3 years ago

@Tomas, just turn off the AHCI feature in the BIOS.
Posted by Steve on 3 years ago

The BSoD for INACCESSIBLE_BOOT_DEVICE is 0x7B instead of 0x5B.

Great tip by the way!
Posted by General Failure on 3 years ago

I wish I knew that 3 years ago when I was setting up Lenovo T43's. Always a pain to reimage.
Posted by Phil on 3 years ago


Posted by eric on 3 years ago

I wish the whole computer world would quit assuming everyone has Windows 7 rather than Windows XP.
Posted by Philip on 3 years ago

No problem during this tweak, i'we noticed some differences.
- startup is faster, cut off some seconds.
- when copying the burst speed stays there a bit more.
- while compressing, the performance in general it's better.
There are no big differences, but it's there. The ncq helps mostly in multitasking.

Posted by Codrut on 3 years ago

I had a issue on the folks Dell XPS One last year. CD-R burning was garbage. Turned out it was a AHCI driver issue. Reason was the Hard drive was Sata and the Burner was a laptop IDE. There a special setting in bios to drive ID#0 drive as SATA and ID#1 as IDE. However one must think here. You can load only one type of driver for the chipset. IDE, SATA, ACHI. The ACHI drive was loaded. Now SATA and ACHI don't have Master channel dma. Yet an IDE burner was connected that required it. So the hard drive works and the DVD/CD burner keeps making bad discs because it does get master channel control which keeps the data stream to the drive constant and at a high buffer level. When burning a disc "red book" places 100 block errors as the maximum before the disc is no good. A loss of the data stream give more 100 block errors and ruins the burn. So.

Be careful going to AHCI here it great to switch but only if all your Disc burning drives are SATA drives. If there IDE you'll break your Disc burning setup. And it most difficult to revert it back once the achi drivers are loaded. It told me day and registry mods to force the Dell to revert back.

In the dell case the 16x burner work like a champ in all the burning applications once reverted the system back to IDE.

Posted by Rock on 3 years ago

Help experts! Error 0x7b BSOD!

I had an Intel D845WN mobo-based PC running Win XP SP2, with 2 ATA IDE HDDs.
After a respectable 10 years of operation, the mobo bricked, and I got a new DH67CL mobo. This mobo doesn't support IDE, therefore I got a Dynamode IDE PCI "Host Storage Controller", tucked it into the PCI slot on the mobo, and connected the two HDDs.
Now, what needs to be done is to do a repair install of Win XP, in order that the system do a new "hardware enumeration" and renew the HAL (Hardware Abstraction Layer).

The problem is, that when I try that, booting from the XP SP2 install disk, it does not offer the repair install option!, but instead goes ahead, loads lots of drivers, then goes: "starting windows", and throws a 0x7b BSOD.

I went into the BIOS and switched from AHCI to IDE: didn't help.

Any help will be appreciated because I'm stuck. Thank In Advance - Gail H
Posted by GailH on 3 years ago

Thank You! Worked with Lenovo Ideapad S12.
Posted by Rainer on 3 years ago

Works great on Win7 X64. Running a WD Caviar Blue SATA-II on an ASUS mobo. Improvements are minor but noticeable.

Make sure the PCI slot is set as a bootable device in your BIOS. If its already set, you may have a "bunk" HSC. 7b code indicates a hardware failure.
Posted by Mike on 3 years ago

This will work with Vista or newer machines. XP does not have this particular key. At least that is what I have found on other sites. This did work for me running Win 7 Ultimate.
ASRock 870 Extreme3
Phenom II X4 3.2 Ghz Black Edition OC 4.1 Ghz
8 GB G.Skill RAM
1 TB Seagate HD
2 TB WD Ext HD
Posted by ReBeL on 3 years ago

In my Windows Vista, I tried to enable this feature, ASUS motherboard with (P5K-E) and WD hard drive, but it is not possible. I put the \"Enable disk write cache\" marked \"Enable advanced performance\", but do not want to activate this feature. If I double-check disk options, this feature is always disabled.
Posted by harrydenzon on 3 years ago

It is a little difficult for me to improve SATA hard disk performance ,who can help me?Thank you.
Posted by feisu716 on 3 years ago

I don't feel any difference
Posted by Debashisa Jena on 3 years ago

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