It wouldn't hurt to go check all the wires. Are you sure you downloaded the right audio drivers? I am assuming you have XP 32 bit. (The realtec drivers on the page cover 32 & 64 bit). The realtec audio driver you loaded is a beta version.
Try installing the one under that one: http://www.asus.com/Motherboards/M3A78EM/HelpDesk_Download/
I'm not sure where that ati driver is coming from. I don't see that listed in the audio download section or the graphics section.
I would uninstall any audio programs from control panel realec and ati. Then remove audio devices from device mgr. If XP starts re-detecting them and asks anything, hit cancel. Install chipset drivers over itself again, then install the realtec driver 22.214.171.12459/126.96.36.199. The ati one is still mysterious to me.
Another thing (if all else fails) would be windows update. See if it shoots any optional updates for your audio devices. There is a possibility of hardware failure due to the power supply issue you had.
I read this: "Check in the BIOS if you have assigned the HD Audio to the FP Connector?
There are 2 setting for the Audio in the BIOS, one is to Enable it and the other is to Direct it to either the back I/O Panel or the FP." Maybe this got changed somehow? Check it.
The ATI driver might be for HDMI audio. This might be set as the default device. Go to control panel/sounds and devices/audio tab. What does it say under sound playback? See if you can switch to realtec there.
Under the volume mixer in xp there are 2 main levels. rt click on speaker icon & select "open volume control". This is the full mixer. Make sure wav & master are up and not muted. Options dropdown can select different audio device settings. Make sure to check both devices.
I never ran an XP install that had an hdmi port, so I'm not sure how XP responds to that.
Edited by FrankOtheMountaiN, 27 September 2014 - 08:45 AM.