[DeathONator]

I dunno if this was just w/ the NF7 or w/ all nForce boards. But it was shown that disabling APIC, and just installing windows w/ PIC allowed for a much better MAX FSB. I have the NF7-S REV2.0, and have installed windows w/ out APIC because I was having difficulties getting a high FSB. Is this true for everyone else or since REV2.0 has the problem been fixed for most people?

If you have an nforce REV2.0 board, let us know your MAX FSB with and/or with out APIC.

Mine was 180mhz w/ APIC, and 229mhz with out. But the whole reason for my low APIC results could have been due to other bad BIOS settings I had at that time. I changed to PIC right after I was only getting 180mhz FSB.

Thanks for your replies and thoughts.

[7h3r4py]

APIC?

[Mustanley]

Running 208FSB with APIC enabled. Does anyone know of a way to disable APIC without having to reinstall WinXP? I tried disabling APIC but windows won't load.

[DeathONator]

No, but you can do a "repair" install. So it will keep all your programs, settings, etc.

[Emericana]

APIC disabled always alllows for higher fsb

[q149]

APIC enabled can give more bandwidth and speed.. i use it On. Most the time i see 0 mhz extra with it off and sometimes even less FSB with it Off, sometimes i see more FSB with it off too.. it's always different on systems, you have to test it yourself(and it's a bitch).

[Banyan]

i had a few problems when i had it enabled...

[treepop]

so with apic disabled you get less memory bandwidth or what?......what exaclty does it do?

[G|-|oST]

OK so how exactly do you do a 'repair' installation? I remember trying it for another reason a long time ago, and it didn't seem to be very straight forward. Can someone tell me exactly whats involved?

[Deathknight]

To do a repair install start off like you are doing a regular windows install on a new hard drive. The installation will detect that a previous version of windows exists and will ask you if you want to repair it.

Currently at 231 fsb with APIC enabled.

Personally I saw little difference in fsb going to apic disabled. I am considering trying it again now that I have tweaked myself to some higher fsb with it enabled. However I believe that overall system performance was hurt by disabling it last time. As carefully as I tried to seperate all of my devices onto seperate irqs there are only so many to go around and apic helps a great deal with that.

[druidelder]

Originally posted by treepop
so with apic disabled you get less memory bandwidth or what?......what exaclty does it do?

The APIC Function BIOS feature is used to enable or disable the motherboard's APIC (Advanced Programmable Interrupt Controller). The APIC is a new distributed set of devices that make up an interrupt controller. In current implementations, it consists of three parts - a local APIC, an I/O APIC and an APIC bus.

The local APIC delivers interrupts to a specific processor so each processor in a system has to have its own local APIC. Therefore, a dual processor system must have two local APICs. Because a local APIC has been integrated into every processor since the debut of the original Intel Pentium P54C processor, there's no need to worry about the number of local APICs.

The I/O APIC is the replacement for the old chained 8259 PIC (Programmable Interrupt Controller) still in use in many motherboards. It collects interrupt signals from I/O devices and send messages to the local APICs via the APIC bus which connects it to the local APICs.

There can be up to eight I/O APICs in a system, each supporting anywhere from 24 (usually) to 64 interrupt lines. As you can see, this allows a lot more IRQs than is currently possible with the 8259 PIC. Note that without at least one I/O APIC, the local APIC is useless and the system functions as if it's based on the 8259 PIC.

To sum it all up, APIC provides multiprocessor support, more IRQs and faster interrupt handling which are not possible with the old 8259 PIC. Although they can be used in single-processor boards, you are more likely to find them in multi-processor motherboards. This is because APIC is only supported in Windows NT, 2000 and XP. It is not supported in operating systems that are required to support MS-DOS device drivers, i.e. Windows 95/98. But as users transition to Windows XP, you can expect more manufacturers to ship single-processor boards with I/O APICs.

If your single-processor motherboard supports APIC and you are using a Win32 operating system (Windows NT, 2000 and XP), it's recommended that you enable this feature to allow faster and better IRQ handling. If you are using a multiprocessor motherboard, you must enable this feature because it's required for IRQ handling in multiprocessor systems.

However, if you are running Windows 95/98 or a DOS-based operating system on a single-processor motherboard, you must disable this feature. This is because MS-DOS drivers assume they can write directly to the 8259 PIC (APIC did not exist yet in those days!) and its associated IDT entries. Disabling this feature forces the APIC to revert to the legacy 8259 PIC mode.

[treepop]

druidelder
thanks for the read......this may sound stupid but erm whats IRQ handling?

[druidelder]

IRQ stands for Interrupt ReQuest. Each device in a system is given its own IRQ (or a channel) that the system uses to talk to it. Say you click your mouse button, it sends an interrupt to the CPU on its channel (IRQ). The CPU takes all of the interrupts and prioritizes them. Then it starts executing commands. The process of receiving the interrupts and prioritizing IRQ usage is called IRQ handling. APIC also allows for more IRQs (channels) that its older sibling PIC, which in turn means more possible devices.

An example: PIC is a traffic cop in the middle of an intersection, directing traffic. APIC is a sensor driven light, faster and more flexible. Traffic moves faster and more smoothly with APIC.

[treepop]

aight thanks again......so it seems the overall performance of your system would be at least 5-10% slower.....so you would have to gain at least 10-20 fsb mhz in doing this....or am I mistaken?