I vaguely recall this (cannot actually disable onboard device) being a pernicious problem with late 90s big-box machines.

I vaguely remember it having something to do with early ISA plug&play, with windows finding the ISA pnp ID, then enabling and configuring the device, while 'disabled' in the bios just left the devices unconfigured.

I recall 'some degree of success' setting the onboard device as disabled in the bios, and the windows driver 'Disabled in this hardware profile', with a force-loaded 'other unsupported device' holder driver assigned, so that windows would not init the card and assign resources.

On some Compaqs there is option in Security - Device Security - Audio (or so, I dont remeber exactly) for onboard sound disabling. Sometimes you must even install new soundcard first, then you can disable onboard.

I once used an IBM motherboard with an integrated CS4235 sound card and encountered the exact same problem: even after disabling the sound card in the BIOS, it could still be detected. Ultimately, I resorted to an extreme measure: I physically removed the CS4235 chip from the motherboard.

Yeah, the BIOSes simply don't initialize the chips that you "disable" but there is no way to actually make them invisible and not speak when something else, such as Windows, goes through the PnP process...

Removal of the chip (which I have done too) will work but it probably is easier to find the reset signal of the chip and put it into permanent reset state.

Ydee wrote on 2026-04-17, 07:22:

On some Compaqs there is option in Security - Device Security - Audio (or so, I dont remeber exactly) for onboard sound disabling. Sometimes you must even install new soundcard first, then you can disable onboard.

You're right. I have no idea why they called it "Device Security" but there I found option that disables sound card. Ridiculous naming.

Tiido wrote on 2026-04-18, 15:08:

Removal of the chip (which I have done too) will work but it probably is easier to find the reset signal of the chip and put it into permanent reset state.

Another, potentially less intimidating, option for some audio controllers is to remove the EEPROM containing the PNP and configuration data. Without that, some devices won't enumerate at all, and will effectively be "disabled". I take pains to specify some because chips like the CS4237 have built-in fallback data (they will still enumerate as a CS4236, which is mostly compatible, though without firmware patches or customised configuration data); CS423x, the InterWave and numerous others can also be initialised via some PNP-bypass method that will often still work, too (IBM used this often, to save the extra cost of the EEPROM and support components).

The FM Synth in the ESS AudioDrive is quite good anyway but with the WDM drivers you can only use it for General MIDI in Windows. If you uninstall those drivers and use the Windows 95/98 VxD drivers for the ES1868 you should have OPL sound in DOS, or apparently you can use this patch with the VxD drivers for the ES1869 to allow DOS audio if you want 48khz and 3-d sound effects: Patching VxD for ES1869 drivers to enable Windows 9x dos box midi support