We've had a few similar threads in the past involving psu noise and mouse movement. There are several possibilites:
1. Deselect Smooth Mouse Scrolling in Internet Options.
2. Disable, turn off, or mute any unused recording inputs
Shovenose ready mentioned a deteriorating capacitor or coil in the psu. Deteriorating capacitors are the most common cause of electrical noise. The capacitors are used in noise suppression circuits. However, the actual bad capacitor may not necessarily be inside the psu. It may be on the motherboard, video card, or other component. Look for a capacitor that is bulging or oddly shaped. It also may have an ugly bownish sticky fluid that leaked out. They are easy to spot.