I've updated my SP3 to windows 10 via fresh install of .iso a few days after it became available, and I use the surface daily (6-10 hours). Took a phone call with Microsoft to upgrade my windows 'key' to 10 but it was worth it. Problem I'm having, is all day yesterday and today, with no user programs/apps running, system fan is on and warm. Inside taskbar it shows system process running 14% cpu, and system interrupts running 7% cpu. Together with a few other backround tasks, this is equaling 25-35% cpu usage. Anyone know what is going on or a fix?