Pretty sure I had a Pentium 4 mobo that was kind of like that in 2002-2003 timeframe. Was still rocking my old ISA Sound Blaster 16 (the big ass one with the connector for a CD-ROM drive) alongside a Radeon 7500 in the AGP slot.
It wasn't much but I could run Alice, Max Payne, GTA 3, Dungeon Siege on there, all at like mid settings, so I was a pretty happy camper for a high school kid putting paper route money into my own PC.
ISA slots were definitely rather rare on motherboards by the time you got to the Pentium 4 era, so that's cool that you managed to find one that also offered DMA, since I believe Sound Blaster cards needed that to properly function.
I think I would have done the same with my AWE64 Gold if that was still an option for me in the early 2000s.
Having googled it a bit now, it's fully possible I have my wires crossed, since I know that P4 machine had the SiS 645 chipset which of course had built in audio.
I definitely used the Sound Blaster with my 486DX100, and I recalled migrating it to at least one other machine after that; it was nice for the joystick port and also the better wavetable synth on classic games.
It wasn't much but I could run Alice, Max Payne, GTA 3, Dungeon Siege on there, all at like mid settings, so I was a pretty happy camper for a high school kid putting paper route money into my own PC.