Motherboard sensor saying the wrong readout is normal. As long as you can physically feel the components and they aren't as hot as the read out says your fine. Kind of a phantom sensor.
i actually used that case for about a year i found the best solution was to have a fan in the front as intake 2 in the top as intake and one in the back as exhaust, i also modded the the side panel to be a full clear window without fan mounts.
Remount your cooler and reapply thermal paste 80c at under 1.2 volts seems kind of high. And make sure to watch your vrm temps because your board doesn't have the best vrm cooling.
i used a hyper 212 evo for about 3 days on my i7 4790k, i would not recommend it. it cant keep up with it the temps get up to 75c under gaming load with a overclock of 4.5ghz 1.19 volts. i would recommend a NHD-14 or master seidon 240m.