So, while sitting in the quiet of an evening after putting my 4,1 -> 5,1 to sleep, I started hearing a weird clicking every 10-15 seconds. Getting down under the desk to track the source, i could hear a faint electrical hum from in the power supply, near where the power cable enters, and that appeared to also be the source of the click / pop. Shutting the machine down, the noise continues (I've got my ear right up to the mesh so I'm pretty sure of the source). Unplugging the power, sound goes away. Opinions? Dust cooking off / shorting on something, or "buy a spare power supply time"? Main concern is safety in terms of shorts / fire. Thanks.