Activating AHCI for SATA drives after Windows OS install

[TerryG]

Typically, AHCI drivers are loaded during the initial Windows OS installation process by hitting F6 at the SCSI driver request prompt. Well, many people (like me) didn't know anything about this, or what AHCI was for that matter, prior to buying a new motherboard and building a new computer.

In my case, the motherboard is the Asus P5Q with the Intel P45 ICH10R Chipset. Up until tonight I'd been running the SATA 3 drives as IDE Enhanced.
Well, I've figured out a way to get everything SATA working as AHCI for improved performance without reinstalling Windows!

*Although I'm describing specific steps and components in my setup, this process will very likely work for other setups/motherboards with some obvious variations for your specific file names, etc.

For ASUS P5Q owners currently running Windows XP or Vista 32/64:

1. Download and expand the latest IH10R_AHCIRAID_XPVista driver package.

2. Open the appropriate 32Bit or 64Bit folder and copy "IaStor.sys" to Windows\system32\drivers.

3. Copy "iaStor.inf" & "iaAHCI.inf" to Windows\inf (in XP you can right click and select Install and Windows will create the corresponding .PNF file - This install won't work the same way in Vista, but don't worry).

4. Then, copy this blue text between the horizontal lines below into a Notepad txt file and rename it to "AHCI_ICH10.reg" (The name isn't really important, just something to ID it for reference. Go through the prompts, .txt files copy to .reg files without issue):

------------------------------------------
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\CriticalDeviceDatabase\pci#ven_8086&dev_3A22&cc_0106]
"Service"="iaStor"
"ClassGUID"="{4D36E96A-E325-11CE-BFC1-08002BE10318}"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\iaStor]
"Type"=dword:00000001
"Start"=dword:00000000
"Group"="SCSI miniport"
"ErrorControl"=dword:00000001
"ImagePath"="system32\\drivers\\iaStor.sys"
"tag"=dword:00000019
"DisplayName"="Intel AHCI Controller"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\iaStor\Parameters]
"queuePriorityEnable"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\iaStor\Enum]
"0"="PCI\\VEN_8086&DEV_3A22&SUBSYS_B0051458&REV_02\\3&13c0b0c5&0&FA"
"Count"=dword:00000001
"NextInstance"=dword:00000001
-------------------------------------------

5. Now, Right click on this .reg file and select MERGE. You'll get a confirmation prompt, say yes and proceed until you get confirmation it was added to your registry.

6. Reboot and hit DEL to enter your Bios setup.

7. Go to: Main/Storage Configuration/SATA Configuration, Configure SATA as:
Select "AHCI".

8. Click F10 to Save & Exit Bios

When you boot into Windows, it will recognize the new device and prompt for driver installation. Browse to the location of your IH10R_AHCIRAID_XPVista driver package folder and follow the prompts.

Reboot, and you're running AHCI! :D

==========

For anyone running a dual boot, you'll need to reset the "Configure SATA as" back to "IDE Enhanced" and boot into the second OS to repeat the procedure.
Otherwise, attempting to boot into the OS that hasn't been configured while your Bios is set to AHCI will result in a Blue Screen error and hard reboot.

Cheers!
:acclaim:

*Note the text inside your .inf files (open in Notepad) specifying your actual components and file names. Cross reference the registry file text above for clues to where you can copy & paste (overwrite) the proper .inf file information (driver name and pci#ven_xxxx... data) for creating a custom registry file for your setup. Yes, you need a certain level of intellect and balls to analyze this and follow through with inserting data into your registry. You won't learn anything if you never try. Good luck.

[The Guru]

When I reformatted my HDD for the first time I thought I had to install the drivers via F6, but a window appeared that said XP had better drivers installed by default.

[TerryG]

When I reformatted my HDD for the first time I thought I had to install the drivers via F6, but a window appeared that said XP had better drivers installed by default.
I suppose that would be the case if your motherboard isn't using newer components requiring newer drivers than the XP disc contains.

[2407WFPHC]

While I haven't tested newer versions of the ICHxxR, I thought Intel's implementation of AHCI and RAID caused DPC issues every few minutes like clockwork? I was always under the impression you wanted to run in regular IDE mode (specifically disable AHCI and RAID) on the intel Southbridge ICH chips? Or is this old folklore along the lines of P-ATA HD's sharing busses and such?

[TerryG]

well, let me fire up my DPC utility and see....

Seems fine.
24 tracks, 6 minute song, UAD-2 Quad at 92% load, RME buffer @ 256 (6mS)
... DPC hovering around 13-22µS latency.. occasional spike to 60... (anything below 500 is still in the green).