1. Buy a AV switchbox from a electronic store. 2. Plug your HDMI cable from your PS3 to your monitor for display. 3. Plug your computer audio in to the switch box, you will need a adapter for this unless your PC speakers came with this. 4. Plug your PS3 AV cables in to the switch box. 5. Setup audio in your PS3 settings for Audio to AV. 6. Flip the switch to alternate between PC or PS3 sound.