CPU Cooling

I have an ASUS P8Z68 with an i7 2600k @3.4G
and 2 questions if you can help:

1) My BIOS idle temp reports around 45-50C under low load (or whatever the BIOS is using). The following
Real Temp, SIW, Core Temp, Probe II all report 25-30C at idle.
Intel diagnostics and Real temp give good temperature gaps under load.

Asus FAQs suggest disabling Report/CPU C3 & C6 but it makes little difference.
I find the BIOS reading meaningless - any suggestions?

2) I'm using a stock cooler which gives me 70C (not BIOS temp!) when running a video encode for a couple of hours. This will rise when the days get hotter.
I'm think of getting either
a) Coolmaster Universal Hyper 212
or the more expensive
b) Noctua NH-D14

Should I just buy the Coolmaster?

I Recommend Hyper TX3 because it has automatic frequency controller, and it cools more efficiently.I personally use this on my AMD PhenomII x2, and I must say it is really light & powerful and makes your CPU faster .

And what do you mean by taking everything out from case?

Then the Hyper TX3 is perfect for your PC.

It should cost around 20-23 €, it has light flexible mountings for both AMD and INTEL CPU's and I have MidTower case and I managed to install it perfectly without removing any other units from case . :)

But just in case:What is the Wattage of you CPU ?
_____
Edit:
I just read that the TX3 doesn't support i7 CPU's so you should get 212 Plus

I went with the Hyper 212 plus. Only cost $32 so I'll see how I go.
Using Prime95 or a full video encode it seems to drop core temps by ~20C over the stock cooler.

My Lancool PC-K60 case has a convenient access cutout on the underside of the motherboard so it didn't need to come out to put the backing plate in.
I'll probably still reinstall the heatsink since it can still rotate!