Device Manager is your best tool for resolving conflicts. To run
   Device Manager, right-click on "My computer" and hit "Properties",
   then hit the Device Manager tab. Any device that failed to start will
   have a (!) identifier with it, indicating some kind of failure.
   Bringing up properties for that device will go into the details.
   
   If your card causes a hardware conflict, you can adjust its settings
   with the Resources tab. If your card uses jumpers, you will need to
   power off the computer and adjust them, before the device will work.
   If it is a software configurable device, adjusting the resources may
   allow the device to start up without having to re-start the computer.
   Sound cards often react like this.
   
   You might have a resource conflict with a real-mode driver, or a Win
   3.1 driver. These you can't resolve using Device Manager, but you can
   tell Device Manager to reserve resources for such devices.
   Double-click on "Computer" in Device Manager, and you can view all
   resources in use, or reserve resources for non-Win95 drivers.
   Reserving memory resources this way works like EMMExclude= lines in
   system.ini.

     * 4.7.1. Help with devices that use IRQ 2 or IRQ 9
       
   Quick background... The first PC compatibles (XTs and 8088s) made
   interrupt lines 2 to 7 available for ISA cards. IRQ 2 was marked as
   "reserved" but was still available for developers. This was handy to
   have because if you had a floppy drive (IRQ 6), two serial ports (IRQs
   3 and 4), and two printer ports (IRQs 5 and 7), you were kinda stuck
   with IRQ 2. MIDI devices are the most common devices that used IRQ 2.
   
   ATs and better added a second interrupt controller (The interrupt
   controller you see in Device Manager is really two interrupt
   controllers cascaded) and the second controller used IRQ 2 to indicate
   an interrupt occured on a line from IRQs 8 to 15. (Remember that IBM
   "reserved" IRQ 2? Now you know why.) To maintain compatibilty with
   devices that used IRQ 2, ATs wired IRQ 9 in place of IRQ 2 on the bus.
   Whenever you install an 8-bit card that allows you to use IRQ 2,
   you're really using IRQ 9. This wasn't enough because those MIDI
   programs wouldn't understand what IRQ 9 was. Every incarnation of DOS,
   from 2.0 up to 6.22, would cascade IRQ 9 events to the IRQ 2 handler
   so these old programs would work. Guess what? Win95 no longer does
   this.
   
   To use devices that allow IRQ 2, set that driver's setting to use IRQ
   9 instead. The MPU-401 MIDI driver defaults to using IRQ 9, for
   example. If you add an 8-bit internal modem to a system that has two
   serial ports and a sound card, you should use IRQ 9 to avoid conflicts
   with the other ports. "Basic Configuratrion 5" for a serial port lets
   you select IRQ 9. Don't even try to use DOS software that attempts to
   use "IRQ 2" because it simply won't work.