I got a Dell OptiPlex GX110 with Windows 98 pre-installed. The hard drive died so I replaced it with a new one that was the same model and got a new install disk for Windows 98. The sound worked perfectly fine before but now the driver is missing and the COMPUTER can't recover it. I'm using an onboard soundcard, the computer says it is a PCI communication device. The color options also seemed to have gotten messed up, I can now only go to 16 colors even though before it could go to 256 colors.Call Dell for the factory retore disc which includes drivers...You will need to load the drivers from the Dell website, yes they still have drivers for your computer running Windows 98. If you have another computer with a CD burner it may be easier to make up the driver install disk to a cd disk. Windows 98 will not access usb pendrives without drivers loaded.

The Dell drivers when downloaded are Zip FILES which self extract to a folder called R then a number. to make then meaningful rename the folders as CHIPSET, Network, etc

Start with the Intel 800 Series INTEGRATED Chipset driver then the Video adapter Intel 810 Series Integrated Video, then Audio Analog Devices AD1881 Integrated Audio

Your computer had the option of 3 different network adaptersf you will need to get the number off the chip. Attached is a picture of the part of the motherboard with the chip

The drivers are available here https://www.dell.com/support/home/en-nz/product-support/product/optiplex-gx110/drivers