I'd be very surprised if your desktop draws .8 kW when you're browsing the web. Your discrete GPU should be drawing around 10 W at idle, and you're averaging <

I'd be very surprised if your desktop draws .8 kW when you're browsing the web. Your discrete GPU should be drawing around 10 W at idle, and you're averaging < 30% of your CPU's < 150 W TDP. That's at most 60W, so with a HDD and some fans and 20% loss in the PSU you're maybe touching 100 W.