Which Dell and Realtech drivers did you use? Can you provide a link to them? If the drivers will not install a PCI card would be a suitable workaround, but I would save that as a last resort unless you don't mind spending the $$$.
Does your computer show any devices with a yellow exclamation mark in Device Manager? And if so, what code does it have for an error if you double-click it? You can get to device manager by right-clicking on My Computer, choose Properties, click the Hardware tab, and click the button for Device Manager.
From my Original Post: DELL Omniplex GX270 XP Pro (Inherited)
Boot shows new hardware detected Audio Controller, but wizard can't install.
( no longer available, deleted it for my next resolution attempt so I can't post code)
Drivers I attempted to install: Don't remember links, as I did so many searches, but came up
as result of lookling for Boston Digital BA735, i'm sure.
R91928 Sound Drivers (Dell Signed) - Pretty sure this was from Dell Site.
Realtech AC97 Audio
Ctl Panel Shows No Audio. Everything Grayed out.
Boot shows new hardware detected Audio Controller, but wizard can't install. (yellow ? other devices)
Realtech download driver Install results in Blue screen.
Dell Download driver Install cannot find component and must quit.
Doesn't all this indicate this unit was shipped without Sound Device?
But cpuid scan found this:
From CPUID Scan:
Description Audio device
Location bus 0 (0x00), device 31 (0x1F), function 5 (0x05)
Vendor ID 0x8086
Model ID 0x24D5
Revision ID 0x02
Cache Line 0x00