Installing Sound Drivers for Windows 8.1 on a HP Pavilion P7-1258
When I tried to install the IDT High Definition Audio Drivers for Windows 8 from the HP website , I got an error about having the wrong operating system because it's checking for Window 8.0 and not 8.1.
The trick to getting around this is to let SP59424.exe expand into the Temp folder (and then leave the installer running so that the temp files don't get deleted) and then run the actual install from there.
So go to %temp% and look for the newest folder in there.
Then inside that folder you will find a src folder and inside that should be a setup file, run this and you will be golden.
Here is information about the driver I'm using: