Recently I changed motherboards and had lots of trouble getting the audio interface on its own IRQ. I was getting an occasional drop-out. So I went hunting.
So, after doing all the winodws things (set restore points often) do the IRQ thing.
BIOS setup: disable all devices not used: on-board audio, serial ports, parallel port, USB, non-used drive channels: SATA, IDE,..... Some BIOS have a setting to disable polling of unused RAMM slots. And so on.
I only one USB device: A USB 1.0 midi interface, and do not use a usb mouse/keyboard, so I disabled usb legacy and usb 2.0.
Then in windows I disabled all USB ports that were not in use.
I was then, finally, able to get the sound card on its own IRQ.
Generic putty color keyboard, wheelmouse, 2 monitors,
grey extension cables for mouse, keyboard, and monitors,
AC extensions, steel and fiberboard 60" table, home-made wooden shelving,....