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#21
This means that your motherboard has 2 PCI-Express slots on it. These are the slots in which you install after market video cards. It is normal to have 1-4 depending on the type of motherboard you have. According to your specs, you have a 4870 video card, and that means it is plugged into one of these 2 slots. Your next challenge is to see if the problem is originating from the empty slot or the one with your video card.
Another thing you could check to troubleshoot is to see if your video card inside has a small black audio wire connected to it coming from somewhere off the motherboard or soundcard if you have one. If you do, and you are using the standard green/black/pink ports in the back for your speakers, then take this wire off your video card and see if this solves anything. Otherwise it could be the PCI-E slot in your motherboard itself or possibly the video card causing a disturbence in the PCI-E slot it's in. What make of PSU do you have? You seem to have enough power but the quality of PSU is important.