What Temperature is Safe For My Processorr

Anywhere from 50C to 75C is fine

Agree 50-80 is fine

what software can I measure it with?

Closer to 50 is much better. I have an upgraded i5 and I run between 45 and 50 most of the time. CPU should run less than 5% utilized more than 95% of the time in normal use. I have RealTemp and it rarely goes above 50 unless I am always pushing it for some reason.

Your BIOS will normally alarm you or shut the PC down if it gets too hot. You shouldn't need any additional software for that.

Try this, to monitor and do much more with that 6700K:

https://downloadcenter.intel.com/download/24075/Intel-Extreme-Tuning-Utility-Intel-XTU-



Installs the Intel® Extreme Tuning Utility (Intel® XTU) version 6.0.2.8.

Intel® XTU is a simple Windows*-based performance tuning software for novice and experienced enthusiasts to overclock, monitor, and stress a system. The software interface exposes a set of robust capabilities common in most enthusiast platforms along with special new features available on new Intel® Processors and Intel® Motherboards.

From this guide:
http://www.tomshardware.co.uk/forum/id-1800828/intel-temperature-guide.html

30C Cool (Idle)
40C Normal
50C Normal (Medium Load)
60C Normal
70C Warm (Heavy Load)
75C Warm
80C Hot (100% Load)

So decent is approx. 30-40C while the CPU is (almost) idle.

I agree with Gary above (and posted such prior). 60 degrees is too high for any normal operation I have.

i use speedfan for monitoring cpu temperatures
http://www.almico.com/speedfan.php

may i ask - why the question?  do you have a problem, or is it only wanting to know ?

i7 6700K temps
Idle: 27 degrees Celsius
Load: 60 degrees Celsius
Temperature ceiling (max)  73 degrees Celsius
Note: over this temp. your computer will automatically shut down to protect the CPU, with little risk of damage having being done from the overheating.

Refer to tomshardware.com: "Temperatures at Full Load (During the Stress Test)"
Link:
http://www.tomshardware.com/reviews/skylake-intel-core-i7-6700k-core-i5-6600k,4252-11.html

"Overclock can be a risky proposition. With the Core i7-6700K, though, it appears to be a worthwhile endeavor. This is not only because the chip overclocks well, achieving a maximum speed somewhere between 12 and 20 percent greater than stock."

Read about overclocking-intel-core-i7-6700k
http://www.digitaltrends.com/computing/overclocking-intel-core-i7-6700k/

"what software can I measure it with?"

To monitor temperature I suggest Core Temp 64 Bit.
Core Temp is a compact, no fuss, small footprint, yet powerful program to monitor processor temperature and other vital information.
Supported Processors
Intel: All Core i3, i5, i7 series.
Link:
http://www.alcpu.com/CoreTemp/

computer huy, may i ask - why the question?  do you have a problem, or is it only wanting to know ?