Optimizing Windows 2000 / XP

Windows 2000 and Windows XP are based on the Windows NT operating system. Unlike other recent Windows versions (Windows 98, 98 SE, Me), Windows 2000 and XP are not internally based on DOS. This complete redesign of the operating system structure allowed Microsoft to create a more modern, more stable and a simply better version of their operating system. Many audio applications in their recent versions are now optimized for Windows 2000 / XP. This means that the newer Microsoft operating systems are already a good choice for many modern audio applications.

Note: if you have to choose between Windows 2000 and Windows XP, the last option (XP) will provide you better performance with most modern mainboards and most audio applications. Many rumours (e.g. spreaded in online discussion forums, etc.) claim that Windows 2000 would be the better option compared to Windows XP. This is simply incorrect and not based on any real facts.

This article deals with the most important issues related to the installation and configuration of both, Windows 2000 and Windows XP. If you have read articles about optimizing Windows 9x/Me for audio before, you will notice that Windows 2000 / XP is actually much easier to 'handle' when it comes to special setups for Audio PCs.

ACPI under Windows 2000

The Automatic Configuration Power Interface (ACPI) functionality of Windows 2000 can be very critical on PCs dedicated to HD-recording. If ACPI is enabled, Windows 2000 will use one IRQ (usually 9, sometimes 11 - depending on the mainboard BIOS) for all PCI and all onboard devices in your system. IRQ sharing generally is not a big problem for modern PCI devices. However, it always affects the performance. As we want that your DSP24 series PCI card works with best possible performance, IRQ sharing should be avoided. In the case of ACPI, the IRQ sharing sometimes even causes bigger conflicts if one of the other devices in the system have problems with ACPI installations. One example: graphic cards with nVidia chipsets are known to cause system crashes or at least performance problems of the DSP24 card when they share their IRQ with our hardware.

This issue is also described detailed by Steinberg in their Knowledgebase [1]. Also the good article from Jose-Maria Catena on www.ProRec.com about Tuning of Windows 2000 for Audio [2] describes ACPI related issues.

When you are installing Windows 2000, disabling ACPI is very easy. Before you install Windows, check your BIOS for the PNP OS INSTALLED setting. Set it to NO or DISABLED. During the installation process, you can select the Standard-PC HAL (Hardware Abstraction Layer) instead of the ACPI-PC HAL. To select this HAL, you need to hit F6 when you are asked to install updated device drivers for HDD controllers (SCSI, ...). Then hit F5 to choose Standard-PC. Check the Microsoft Knowledge Base [3] to get more information about HALs.

If Windows 2000 is already installed, it is also possible to replace the ACPI-PC HAL with the Standard-PC HAL. It is important to know that the process that is described in the next few lines is risky in certain configurations and not recommended at all. To stay on the safe side, it is better to directly re-install Windows 2000 as described above with Standard-PC.

Make sure that the PNP OS INSTALLED setting in your BIOS is disabled. No open the Device Manager (Control Panel > System > Hardware > Device Manager). Check the Computer section. Under it, you will see an entry that is called ACPI-PC when ACPI is enabled. When ACPI is not enabled, you will see an entry called Standard-PC instead (as on the picture).

Now double click on ACPI-PC. Continue with Driver > Update Driver > Display a list of the known drivers for this device > Show all hardware of this device class. In the list dialog, you can select Standard-PC now. Confirm your selection. Windows 2000 will reboot your system after that. Note that all device drivers for all your hardware components are re-installed then because the IRQ assignment from your BIOS will be used. Once the process is completed, check the Device Manager again. It should have a Standard-PC entry as on this picture now.

ACPI under Windows XP

The possible performance problems that are mentioned in the section above for Windows 2000 resulted in some changes to improve ACPI functionality under Windows XP. On many systems, the selection of the ACPI-PC HAL instead of Standard-PC will provide better performance. New developments on modern mainboards like APIC (Advanced Programmable Interrupt Controller; don't confuse this with ACPI) allow Windows XP to assign / use different IRQs for different hardware components even if the ACPI-PC HAL is used.

As a general and simplified rule: on older systems, Standard-PC is recommended under Windows XP. On newer systems, the ACPI-PC HAL should be prefered under Windows XP. If you run into problems, change it later. Under Windows 2000, Standard-PC is recommended in any case. To explain this for Windows XP more detailed, check this table with major mainboard chipsets:

Chipsets CPU typical mainboards prefered HAL comment
440BX, 440LX (Intel) Pentium II/III, Celeron Gigabyte 6-BXC, Asus P2B, Asus CUBX, ... Standard-PC -
i815 (Intel) Pentium II/III, Celeron Asus CUSL2-C, Asus TUSL2-C, ... Standard-PC -
i845 series (Intel) Pentium 4 MSI 845 Max, Asus P4B series, ... ACPI-PC enable APIC in BIOS, if this option is not available, use Standard-PC
i850 series (Intel) Pentium 4 Asus P4T-E, MSI 850 Pro, ... ACPI-PC enable APIC in BIOS, some boards do not support APIC and need a BIOS update, use Standard-PC when there are problems with IRQ assignment
KX133, KT133, KT133A, KT266 (VIA) Athlon series, Duron Asus A7V133, EPoX 8KTA3 Pro, MSI K7T, ... Standard-PC the used PCI slot for the DSP24 is important to make sure the card gets its own unshared IRQ
KT266A, KT333, KT400 (VIA) Athlon series, Duron Asus A7V333, MSI K7T266 Pro2-A, ... ACPI-PC only if your BIOS supports APIC and if it is enabled, use Standard PC when this is not available
AMD761, AMD751 (AMD) Athlon series, Duron Asus A7M266, Gigabyte 7DXR+, ... Standard-PC the used PCI slot for the DSP24 is important to make sure the card gets its own unshared IRQ
nForce 415, 420 (nVidia) Athlon series, Duron MSI K7N420 Pro, Asus A7N266-C, ... ACPI-PC enable APIC in BIOS before you install Windows XP
735, 745 (SiS) Athlon series, Duron ECS K7S5A, Asus A7S333, ... ACPI-PC enable APIC in BIOS if available
645, 648 (SiS) Pentium 4 MSI 648 Max, MSI 645E Max-U, ... ACPI-PC enable APIC in BIOS if available

For example: if you use an ASUS A7M266, which is based on the AMD761 chipset, you should disable ACPI and use the Standard-PC HAL instead under Windows XP. Please refer to the instructions for Windows 2000 above to learn how to select Standard-PC instead of ACPI-PC.

Notes: Please do not confuse APIC with ACPI when you check the table above. The typical mainboards column contains usually mainboards that we have recommended or tested/used because they are (or have been) more famous. Of course we cannot list all mainboards. Also some -not so common- chipsets are missing in the table.


When you are using the Standard-PC HAL as recommended, you may find that Windows will not turn off the power of your PC when you shutdown the system. To change this, you need to enable Advanced Power Management (APM). Goto Control Panel > Power Management > Power Options and enable APM. Note that enabling APM requires APM support to be enabled in your mainboard BIOS as well. Some mainboards (like nVidia nForce based solutions) do not support APM.

Background services

Some software vendors recommend their users to change the processor scheduling option from Programs to Background services, e.g. Steinberg [4]. We noticed that especially Cubase VST and Nuendo from Steinberg but also other programs are working better when you use small buffer settings (low-latency). Interestingly, some articles about Windows 2000 / XP audio tuning claim that this tweak does not help at all and even reduces the performance of your system. Our recomendation: try it, but if you use ASIO based software by Steinberg, your system will definitly run better with this tweak. Under Windows 2000 (not XP), goto Control Panel > System > Advanced > Performance Options and select Background services. Under Windows XP, goto Control Panel > System > Advanced > Settings > Advanced > Processor scheduling and select Background services.

Default playback device / Microsoft GS Synthesizer

Windows 2000 and XP both contain the so-called Microsoft GS Synthesizer. This software synthesizer emulates a simple Roland GS sound module. The sound quality is not excellent but OK to listen to GM/GS MIDI files. Sadly, the latency of this software synthesizer is too high to use it for music creation inside a sequencer software. The offset / delay to other tracks is simply too big. Even worse: the software synthesizer is not only unusable for music production, it also can cause potential trouble.

The Microsoft GS Synthesizer always uses the default playback device that has been selected under Control Panel > Sounds/Multimedia > Audio > Prefered Playback Device. If you select ADSP24 Ext. Audio Device 1/2 as default device (channel 1/2 of the external box if you use a DSP24 or DSP24 MK II, the RCA output if you use a DSP24 Value or the monitor output if you use a DSP24 ADAT card), the Microsoft GS Synthesizer will have a conflict with the ASIO driver of your DSP24 series card. Because of that, we strongly recommend to use the Internal Mixer [5] audio device instead. Please select ADSP24 Int. Audio Device as prefered playback device.

To avoid conflicts with the Microsoft GS Synthesizer, you can also make sure that your audio application does not use the corresponding MIDI output device. For example, if you use Cubase VST by Steinberg, disable the MIDI device in the Setup MME software that is accessable from your Startmenu (you need to use at least v5.1 of Cubase VST if you are running Windows XP).

Visual Effects

We strongly recommend to disable all those fancy effects when displaying a menu or tool tip for example - especially of Windows XP. OK, I admit that they may look nice - the problem is that they eat more CPU power as you may think. These effects have a relative high priority among all the tasks running on your system. This means that you might get drop-outs when you open a menu, switch between apps or move a window while you use the audio hardware. Right click on the desktop and select Properties > Appearance > Effects. Now disable everyhing you can live without (that really should be everything in this dialog).

Power Management for HDDs

Also to improve the performance, it is preferable to disable the automatic hard disk power down. By default, Windows will shut down your hard drive after some time of inactivity. Because your HDD then has to power back up the next time it's accessed, your system will slow down for a short while. Open Control Panel > Power Management > Power Options > Home/Office Desk and set Turn off hard disks to Never.

>> Back to Knowledge Base <<

last updated: 11/10/2002 author: Claus Riethmüller

References to other documents or external websites

[1] ACPI kills audio performance, article on the Steinberg Knowledgebase (based on a text from audiocard vendor RME)
[2] Tuning Windows 2000 for Audio, article by Jose-Maria Catena on www.ProRec.com
[3] Windows 2000 HAL issues, article about Hardware Abstraction Layer issues from Microsoft
[4] Optimize processor scheduling for Windows 2000/XP, article on the Steinberg Knowledgebase (based on a text from audiocard vendor RME)
[5] The Internal Mixer, ST Audio Knowledge Base

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