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Win install on nForce2 mb

APIC no APIC solutions , crashes ? by SYAR2003
Posted: 19 Nov 03

Advanced Programmable Interrupt Controller
Should i have it or should i not
Old way IRQ handling/sharing or new one.

W98/ME/LINUX users DISABLE APIC 1.4 version.

Windows2000/XP supports the advanced programmable interrupt controller (APIC) using MPS version 1.4.
APIC distribuate a set of devices that form an interrupt controller by connecting to a local APIC bus.

APIC expand to 24 IRQs and sharing of IRQs.
In Windows2000/XP with APIC enabled, it will show 24 IRQs instead of the classic 15 or less  .

On nForce2 chipsets enabling APIC can result in some minor performance hit in I/O itensive applications.
Systems seems to prefer to run the old-fashioned way.
Drawback with old way is less flexible assignments for interrupt requests ,but if you are not loaded with devices
this option can be concidered.
I suspect higher access latencys for the tha devices in APIC mode compared to the IRQ assignment without APIC is the reason for difference.


APIC ENABLED:
There are 24 different IRQs possible and it could be no sharing. However at "System Information"
some of the IRQs are unused ,and there is still sharing between e.g. the IDE controllers,USB and ethernet controller.Why this is i don't know.
 

APIC DISABLED: 15 IRQs are available and is schared between devices.
The assignments of IRQs is very different from with the APIC enbled situation.

 
WHAT EFFECTS YOU:
With APIC enabled there is possible with more device support without IRQ sharing.

Without APIC you have more sharing but devices that have been assigned their own exclusive IRQs or may be running faster.With disabled it seems you have better contol yourself.And there has been benchmark that shows small
improvments in speed for some devices.

The previous NVIDIA SW-IDE driver
You install 2000/XP loads the drivers from the mb cd.
And........
Answers yes to intsll the SW-IDE .Resultingt in complete crashes and possibly corrupting HDDs files.
Supposedly the earlier sw-ide driver bundled in chipset versions older than 3.13 didn't support APIC .Nvidia also removed the sw-ide driver from their unified 2.45 release leaving the users to run with the microsoft ide driver.

Be aware that switching from APIC enabled to disabled mode in BIOS does require a complete reinstallation of the operating system.(boot problems)
So you have to choose this prior to installing 2000/XP .


SYAR

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