I bought a used GX520 and the volume does not

if it says no audio device then the computer is not recognizing the "soundmax" sound card. you either need to go online to the soundmax website, search for updated drivers, find your version of theyre soundcard (soundmax digital audio) and download the new drivers. then go back to device manager, find the soundcard under sounds and audio devices, right click and chose properties, click the driver tab and choose update driver. it should then prompt you for the location of the driver at which point you enter the location of where you saved the driver you downloaded off theyre website.
or you could also replace the soundcard with a new one which includes its own drivers on a disc.
hope this helps. please rate me. thanks and good luck!

sounds like ( no pun intended) your missing the audio drivers or controllers--right-click on MY COMPUTER then PROPERTIES then HARDWARE then DEVICE MANAGER and check if there are any yellow or red "X"s next to anything (you sound driver) right click and select update driver (you need to be connected to the internet)