ACPI {Advanced Configuration and Power Interface} just means it's compatible with power management {e.g. low power states sleep/hibernation/etc}.
Therefore, if you have an onboard audio driver you must use the driver specific to your MOBO.
Q - What MOBO {motherboard} do you have and what EXACT conflict are you having with the onboard Audio?
Suggestion, open the Device Manager | expand [+] Sound, Video and Gaming... {click e.g. Realtek or your onboard sound driver} | right-click & select Properties | click the Resources -tab -> if it says No then you problems lies somewhere else.
Otherwise:
open the Device Manager | expand [+] Sound, Video and Gaming... {click e.g. Realtek or your onboard sound driver} | right-click Uninstall then Reboot your system. In addition, look for ANY devices listed in the Device Manager tree and those with (?) right-click to uninstall and reboot your system.
If that fails then post the following by pressing the [ALT and PrtScn buttons], save as JPEG image and post {free website http://photobucket.com/ } example: