High load temps on 4670k

The first thing about overclocking is that it's never an exact science, so your results will differ from everyone else's.

Yes, increased voltage leads to higher temperature, but the temperature you're seeing is nothing to worry about. It's debateable how high you should go, but I personally don't like to go beyond 70C. That way, I have some headroom in the summer, when the ambient temperature is higher.

66 degrees isn't really hot. You should start worrying after like 75 degrees. This is fine.

yes.

On 150w Intel, the dh-14 will run @15 C over ambient at max speed, and @17 C over ambient on low (about 900rpm). That said, even at 82F, its not uncommon for a Hyper212 EVO to have temps like you show @ 4.3ish on a 4670k.

I'm pushing 4.4, 1.208v on a 3570k cooled by a h-55, and after 2hrs of prime95 maxed out at 74C.
With that dh-14, you should be in the 50's, 60ish tops at 4.2. Granted your CPU runs hotter than mine from the outset, but that's a top rated cooler, mines on the bottom lol.

While your temps are acceptable, and you are perfectly safe and have no worries about burning up your CPU, I still believe they should be better with that cooler. Could be something as simple as bad case airflow, dusty clogged tower fins, too much paste on CPU. Dunno.

The R2 Midi is a fantastic case, although it maybe beneficial to you to move the intake to the lower position and remove the lower hdd bay to maximize cooler airflow.

Too much paste is as bad as too little, and even though the hottest part of the cpu may be covered, you may have gappage towards the outer edges, you'll find out if/when you take a look. A drop the size of about a small pea or a grain of rice is recommended. Also you must ensure the cooler is tightened correctly, snugged down evenly in an 'X' pattern, then 1/8 - 1/4 turn on each screw till it gets hard on the fingertips and you are thinking hard about grabbing a screwdriver. Noctua makes one of the best fastening systems so you should be good there.

Are you even seeing max speed on the cpu fans? Do you have fan software installed and running maybe that you haven't set yet? If maybe so, then you could either set that, or disable and let bios settings work. Most bios I know of run max duty cycle at 70C. Your case has a fan controller, are your case fans set on that or mobo, if controller, is it up at 12v or set low, where possibly you are not getting good airflow at the higher case temps. Those are pretty good fans and in that case are not all that loud when maxed out.

Sorry if it seems like a lot.

maybe you check the benchmarks for your cooler and if the temps are lower in the benchmarks reapplly the thermal paste properly

HWMonitor won't show any fan speeds because there is no return to the motherboard, the fans are fed from the psu and controlled by the switch. If you want to have bios or software control of the fans you'd need to attach them directly to the motherboard. As for the CPU fan, 'standard' means it will ramp up to a faster speed than 'quiet' and do so at a faster rate. The bios does not care about your temps, it only cares about its temps and this is probably why you are getting what I believe to be higher than usual temps from that cooler. At anything under 70C, the bios is not going to use 100% max duty cycle, its only going to ramp up to what it needs in order to maintain less than 70C.

So, you can change this in the bios, either set it to 'performance' or 'extreme' or whatever the top ranks is, or actually manually change the duty cycle to set a minimum of say 60% (that's about 60% of the speed your fans are capable of) and max duty cycle temp, say 50C, so if and when your cpu reaches 50C, the fans ramp up to 100%. That's whats called 'setting a fan curve', you are manually stating the boundries. There is more than a few software programs that will do this for you, and have nice little graphs and pictures etc that you run through Windows. Asus has Fan Xpert, MSi has Core Center etc. Whatever your motherboard is, it will have a utility such as this. I'd also recommend you put the fans on the mobo too, having them auto monitored and controlled to keep case temps down I believe is better than doing it manually. You can also set fan curves for them too, so all is cool and quiet when idle but will ramp up when the cpu is very active.

As far as noise is concerned, the case will dampen most of it, but if you can live with a few extra degrees of heat, you'll be able to turn the fans down a little.

Yes. Point the cpu fan exhaust towards the back, that is correct. The 120mm fan takes cool air, blows it through the first bank of fins, where the 140mm fan picks it up and sends it through the second bank of fins and then the case rear exhaust picks it up and shoves it out the back.

Basically, 'standard' is doing you an injustice, you really need to take control of all your fans and optimize them for your tastes, not so much the cpu's requirements