ok, so i think i've hit the jackpot with this OS! I've spent nearly 10x more time configuring it than all of the previous windows versions combined. needless to say, its so bad, that i've had to resort to wasting time searching for regedits and hacks just to make it usable. so back to the topic. i've had the exact same problem, but someone here mentioned the power states. i had to turn mine off as well as cool n' quiet on my amd board because these two were just dragging down the performance of my pc. my new sandisk extreme pro was getting single digit 4k reads and writes in crystal diskmark. once i turned off all these power saving features, the performance shot through the roof! i am now getting 8 times the performance numbers, mainly what other review sites are reporting on their benchmarks! chances are, your power save states might be turned off as well, which is why the pc isnt shutting down completely under winblows 8. i'm sure you've figured out by now how to deal with the not shutting down problem...control panel>power options>choose what the power buttons do>change settings>uncheck the "turn on fast startup".