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Installing ACPI after Windows installed

Is it possible to install ACPI after Windows has been installed. I disabled ACPI in the BIOS before i installed Windows due to IRQ conflicts if it was enabled. With it disabled it seems that Windows uses IRQ's up to 128, so there are no conflicts now. With ACPI enabled I get a lot of IRQ conflicts, for example the onboard RAID-controller, AGP and first PCI-slot share the same PIN setting in BIOS which results in that they will share the same IRQ in Windows IF ACPI is enabled. This has been quite a dilemma for me, to enable or disable the ACPI. I understand that it is ok for cards to share IRQ's and I want to try my system with ACPI enabled to see if it's stable. Any thoughts on this are welcome.


EpoX D3VA ( VIA Apollo 133a chipset )
Creative labs GeForce2 GTS 32Mb
D-link DFE-500TX ethernet card
Soundblaster Audigy Gamer
SiS6326 PCI ( secondary video card )
Hauppauge WinTV PCI
60Gb Western Digital Caviar ATA 100 ( OS on this, runs on ATA66 )
2 x 45Gb IBM Deskstar 75GXP ( RAID0 )
5.1Gb Quantum fireball
Lite-on cd-burner 16/10/40
Standard floppy drive
300W Power supply
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1 Solution
Go ahead and give it a try. You can enable ACPI with Windows installed. Backup the registry and the Windows directory befor starting just in case something goes wrong you have a way back. I know XP has a System Retore feature which I beleive can be used from Safe Mode but I a am a big believer in backing up the registry and the Windows directory as an adde precaution.

The Crazy One
although this is for Win2000 I think it is still worth the read.

Here is a little article that you might find iteresting



Repair, Recovery, and Restore
Restoring the Registry
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Reprinted with permission from the Windows 2000 Resource Kits
When you back up the system state data, a copy of your registry files is also saved in %SystemRoot%\Repair\Regback. If your registry files become corrupted or are accidentally erased, you can use these files to repair the registry without performing a full restore of the system state data. This method is recommended only for advanced users.


Backup does not allow you to restore only the registry files. If you use Backup to restore lost data to the registry, all system state data is replaced.

You can also use Backup to restore lost data to the registry. The system must be stable enough for you to open Backup. If your computer cannot start, you might be able to repair the operating system using an ERD. The Fast Repair option of the Emergency Repair Process checks and, if necessary, replaces each registry key by copying it from the repair directory to the folder %SystemRoot%\Config.

If you cannot fix the problem with the registry by performing the Emergency Repair Process or by selecting Last Known Good Configuration from the Windows 2000 Advanced Options menu, it might be necessary to reinstall the operating system and device drivers and to reconfigure the system before you can restore the data.

COPYRIGHT NOTICE. Copyright 2002 Microsoft Corporation, One Microsoft Way, Redmond, Washington 98052-6399 U.S.A. All rights reserved.
To backup the registry

Start > Programs > Accessories > Backup > click on the  "Emergency Repair Disk" button. Now click on the portion

labeled "Also backup registry........." put a floopy disk in and then hit the Ok button.
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foxeyeAuthor Commented:
Hmm, yes but enabling ACPI in BIOS does nothing. How do I make Windows detect the changes. The usual "Add hardware" approach doesn't do it.
You need to go to device manager, open computer, right click on the item listed underneath and choose update driver. Next, choose driver from list or add manually and add the acpi pc driver and then restart the machine. Be very, very careful as if it is not compatible, you will blue screen your pc and not be able to boot.
I'm afraid I have some bad news for you
The change from non-ACPI to ACPI by changing drivers is not supported. To properly make this change, an in-place upgrade (where the computer is converted to ACPI during Setup) is mandatory
I thought I remembered something like that but I wasn't sure.
Thanks for the excellent grade, and I wish it was better news
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