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APIC Mode??? What is that?

Discussion in 'Hardware Discussion & Support' started by Candyman, Jul 6, 2002.

  1. Candyman

    Candyman [DH] Lover!

    I just got a new Abit KX7-333 motherboard and I see that there is a setting to enable/disable in the BIOS called APIC Mode. Does anyone know what that does? Should I enable it or disable it?

    I hope the Abit dude is reading this.... :D
  2. sinjin

    sinjin the last samurai

    apic = advanced programmable interrupt controller or something to that effect...

    i think it is for managing the interrupts on a multiprocessor system...but if you only have a single cpu enabling can improve performance.
  3. Candyman

    Candyman [DH] Lover!


    Enabling will improve???? Is that a typo?
  4. sinjin

    sinjin the last samurai

    yea i think so...it enables 24 lines of interrupt request lines rather than 16 (or something like that)...there has to be documentation on this somewhere...
  5. sinjin

    sinjin the last samurai

  6. Candyman

    Candyman [DH] Lover!

    I had it diabled by default.....however, when I enable it and save settings to reboot....nothing happens! Just a black screen. I go back to disable it and save/reboot and everything works again.....don't tell me I have to reformat to enable this setting... :(
  7. sinjin

    sinjin the last samurai

    changing between enabled and disabled APIC mode may require you to reinstall Windows to allow a different hardware access layer to be used...
  8. ajm786

    ajm786 New Member

    No, as far as I am concerened, you MUST re-install Windows. I've tried it before.

    And as for me, I now always leave APIC on. You do get better performance and more IRQs.
  9. shuki

    shuki New Member

    not to be contradictory but I read twice to disable APIC. sorry don't have any links but just would recommend more info on the subject before reformatting....
  10. ajm786

    ajm786 New Member

    You have to reformat either way, to avoid hosing your system.

    Don't get confused with ACPI and APIC. ACPI is the standard for power saving, etc. etc. etc. implemented by Microsoft, which you will find in Windows. Go ahead. In you device manager, you will see that all your devices use one IRQ. THAT IS CALLED ACPI.

    APIC is an option in your BIOS that stretches your IRQs from the standard AT of 15 to about 23 or 24, so that all your devices don't use one IRQ. THAT IS APIC.
  11. shuki

    shuki New Member


    not to highjack the thread or anything ;) but how do you disable ACPI in windows?
  12. shuki

    shuki New Member

  13. Gurm

    Gurm Hail to the King, Baby!

    Both ACPI _and_ APIC are good to have on. Don't disable either. Doing so only encourages the hardware manufacturers to make bad non-compliant hardware. You'll do TONS more work shuffling IRQ's (since despite APIC, in non-ACPI mode you only get 4 hardware-level interrupts - that's right ONLY 4!), and get almost no performance benefits. No matter what anyone told you, ACPI = GOOD.

    - Gurm
  14. misae

    misae New Member


    I agree with you on this one and by one hundred and fifty percent. Removing ACPI changes your OS kernel extensively and you may be left with a lot of features missing e.g. UDMA on your IDE drives etc because your IDE controller is trying to share the IRQ with your graphics card. (Well it did happen to me.. in fact I lost my 2ndary IDE altogether!... had to do a full format to fix it).

    Once you disable ACPI from the BIOS and then the OS you cannot 'simply' turn it back on. Even with a system restore point set you may run into problems.

    APIC though is slightly different as previously mentioned. :)
  15. radTube

    radTube just keepin' it cool

    For some reason or another APIC made my system unstable. I did reistall windows after enabling it (actually I just enabled APIC right before I had to reinstall anyway), but had random lockouts afterwards. Everything's stable again now that I've disabled it. And I didn't have to reinstall Windows (XP) this time.
  16. Ver

    Ver New Member

    From my understaning, APIC is quite useless unless you have more than on cpu.
  17. sjohnson

    sjohnson New Member


    Um-hum - so I should trash-can my nVidia GF2 because it shares an interrupt with the LAN card in Win2k and I can't tell Win2k to assign it a unique IRQ when ACPI is enabled on a new install? I guess I can then take my chances on buying a new $400 nVidia card and hope that the drivers and hardware for this rather critical piece of hardware aren't "bad non-compliant" crashing and stuttering additions to my system?

    Or, should I install as a Standard PC, spend 10 minutes assigning IRQ's and have a smooth running system with my existing GF2?

    ACPI is the savior of MIS system integrators - makes installation and support a breeze. This is because, in a coporate environment any employee to tries to push their system with games or other 3D applications is rarely tolerated.

    But for a gaming enthusiast, I can either spend beau-coup bux on the latest and greatest, then pray a LOT, and struggle with drivers and PCI slots and HOPE everything runs well when the system is stressed - or - Standard PC. Never say never and never say always :)

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