ASUS M4A78 Pro SATA 3 Gb/s setup

I've been running my SATA drives in IDE emulation mode, the default in BIOS setup on this ASUS M4A78 Pro mobo. I believe this limits the drive performance and would like to change to true SATA setup. (I no longer have any PATA devices in my system.) But when I go into BIOS setup and change the Storage configuration setting from IDE to AHCI the system will no longer boot into Vista Home Premium and asks me to put in the Vista setup disk and run a repair installation.

I don't want to risk making my drives unreadable and losing vital data, so I'm asking here what to do.

There's a warning in the manual and in BIOS setup that in AHCI mode the onboard SATA controller chip will only recognize drives attached to SATA 1 thru SATA 4 channels, and that a driver is required so that the operating system can read all six SATA channels.

So where is the AHCI driver? On the MOBO disk? On the Vista install disk? Downloaded from somewhere?

I get all confused :pt1cable: because I'm not trying to create a RAID array, I just want to get full 3Gb/s performance from my drives.

I'm also preparing to install Win 7 on a blank HD.
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  1. Best answer
    Are you going to dual-boot vista with win 7?
    If not then wait until you install 7 and switch it to AHCI mode.
    Look here:
  2. I am dual-booting Win7 and Vista now, but I installed Win7 on a bare drive with IDE mode. So I have Vista on one drive and Win7 on the other, both of them set up under IDE emulation. So can I switch to AHCI now, boot from the Win7 disk and restore the boot info to get it working that way? Or do I have to start over and do a clean install of Win7 under AHCI? Thing is, I don't want to lose access to everything on my 5 HDs that are formatted under IDE.
  3. Problem solved. I followed the link provided by sturm and got Microsoft's explanation of how to edit the registry to enable the AHCI drivers. I did that for both Win 7 and Vista installations. Then rebooted, ran BIOS setup and enabled AHCI mode in Storage settings. Both versions of Windows then discovered the drives in AHCI mode and installed the necessary drivers. Now I'm up to speed.

    Microsoft Knowledgebase article describing how to enable the AHCI drivers via the registry:

  4. Best answer selected by nwilson941.
  5. I originally missed the last few comments here, but was going to suggest basically the same solution (, just an explanation rather then the link but then seen it was solved... i ran into a situation last night with this and found for some reason AHCI was not enabled just IDE and did this but windows (installing clean) wouldn't recognize the drive at all.

    BIOS has some odd settings with the SATA channels, You can set all Ports to IDE (6 total) (1-4) could be set to AHCI and ports 5 and 6 could also but, if ports 1-4 were set to IDE, then you could not set 5/6 to AHCI.

    I tried it both ways and swapped sata cable around never could get it to detect the drive during 7 install...newer SATA II (3Gbit) 7200 rpm western digital drive but it would not boot properly even after installing set to IDE then applying the fix from the link for some reason.
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