>D) I/O address conflect between the sound card and NIC.
>
>300-330 and 310-340 are Ranges of I/O addresses so they
>overlap.
>
>I have never seen a problem with a device in IRQ 2 if IRQ 9
>is not used, any device in IRQ 2 is going to appear to the
>system as IRQ 9
>

Bernard's answer to the OP's question is of course correct regarding the I/O ranges overlapping. However, the rest of his response can be a little bit misleading...

As was stated by Ropera, IRQ2 is used as a cascaded input to the primary interrupt controller. This began when the ISA slot was modified from its 8-bit configuration into its 16-bit version. At that time, the ISA slot pin for IRQ2 (Pin B4) was reassigned to IRQ9 -- but only for the 16-bit version of the ISA slot! This could -- and did -- lead to IRQ problems as explained below.

In many systems that used a mix of 8-bit and 16-bit ISA slots, it was possible to inadvertantly block the use of IRQ9 by installing a hardware device into an 8-bit slot if that device was configured to use IRQ2. If that same device was installed into the 8-bit portion of a 16-bit ISA slot, it would use IRQ9 even though the device was set to IRQ2. Having such a device configured as above and installed into an 8-bit slot would preclude the concurrent use of IRQ9. Further, if such a device were to be configured and installed in that manner -- in an 8-bit slot and using IRQ2, it would also cause problems with any devices using the higher (16-bit) IRQ's that are managed by the scondary interrupt controller, as those interrupts are passed to the CPU via the cascaded input through IRQ2.

Fortunately, this problem has all but gone away. This is due to:

• the development and implementation of the PCI slot;
  
• the development and implementation of advanced mainboard chipsets;
  
• the development and implementation of ACPI-compliant BIOS'es;
  
• the development and implementation of ACPI-compliant operating systems; and
  
• the phasing out of ISA slots -- both 8-bit and 16-bit

To read more about how IRQ's work in a basic (pre-ACPI) system, click here.