When I put it in sleep mode there are scratching noises inside of the Surface, louder in the corner where the power button is. It sounds... like crackling, but not really 100% like electrical crackle on, say, a defective power supply (you know what I'm talking about). It's perfectly silent when working though. Wasn't even really loud during initial updates or anything. This bugs me a bit and I'm not using Sleep mode as a result. I don't really mind all that much not using Sleep mode, but you know, for the money I'd rather it be perfect... Anyone else experienced this? Should I be concerned at all? Maybe run some tests/benchmarks to see how it behaves under load?..