CraptacularOne
The problem with 8700K's is that they do not have have their IHS soldered so temp consistency between them isn't as uniform among them. Having said that there could be any number of things contributing to the temps. Could be where your case is at it isn't getting good air flow, could be a uneven mount of the cooler, could be a concave/convex IHS in which case only lapping the CPU would help.....ect.
 
I'm seeing mid 60's in game in the pic you provided and that's just fine at load. The max temps you can pretty much ignore as they are just spikes and not indicative of your average consistent running temps unless they are spiking to 100C or so. 

xTemon
 
 
Honestly, your GPU AIO is going to produce more heat than the CPU AIO, and you've got it blowing into the chassis. Usually the front is a cool air intake on a fully Air cooled system. I'd probably have the AIO for the GPU somewhere else, blowing out. Use the Front panel to draw in cool air. You're basically pushing hot air into the system then trying to push it back out through the CPU AIO. It's obviously still performing well enough, but I expect that's mostly because you're drawing air in through other areas with a negative pressure system.
 
 I mounted my AIO on the front panel for the CPU CLC, and I hesitated about that, but decided to do it anyway because the front has the Filter on it, and I wanted to keep the AIO relatively clean. I've got 2 fans exhausting on top, and 1 on the rear however, so it should be pulling cool air through the AIO and whatever heat is disipated into the chassis from the AIO should get vented quickly. Seems to work alright. My temps idled at 30-33 C initially, and 1 day later, (same AIO as old build, new motherboard and CPU), they're down to 29-30. That could be slightly lower ambient, but it doesn't feel cooler today. Quite the opposite actually. 
 
 What's odd about yours though, is the difference between coolant temps and CPU temps. That's quite a stretch. Comparatively, mine is about 2 degrees difference on average, somewhat more under load. I'd suggest you may want to see about remounting the AIO using some decent thermal paste. And have a look at where your spread was on the initial mounting.