Hey i bought a Radeon HD 5770 and an HDMI MNTR ACER|LED 21.5" 5MS S211HLBID R to go with it. After installation of the devices into my computer and installing the Radeon Drivers there was no more sound. I am using the AMD HDMI device set up as my default sound device as was told to have set up. Only thing i can think of though is to try to change the bios when restarting my computer for the sound as i have seen on many forums. But i would rather use another method before trying this out quite yet. Which makes me think that my sound card maybe doesn't support HDMI sound or something and if there was sound cards that could support HDMI it would be appreciative if you could mention something of the sort.