They hum, even when not connected to the sound card. Then the problem is not likely a ground loop, but rather in the speakers' power supply. It'll have to be repaired or replaced.

If you're a dedicated Logitech enthusiast with a compatible Logitech G mouse and don't mind being limited to the included soft cloth mouse pad, the Powerplay 2 works well enough for its intended job.

Today, Logitech is changing that with the Logitech G309, an $80 mouse that almost does it all. It’s the first Powerplay mouse this inexpensive, the first with Bluetooth, the first that lets you ...

For example, an 80 Plus White 500W power supply at 50-percent load would work out to 250W DC power, or 312.5W AC power. You’ll use that latter number (312.5) when tabulating your electricity ...