No that's a totally fine temp. It wouldn't start throttling for another 20 degrees. It does seem like your CPU may be bottlenecking the card though. If it's at 100% then it cant keep up with the GPU and you'll see fps drops at random times. The 1070 is a demanding card, and a 6500 is the minimum you'll need to run it.
There's not really much you can do except overclock your CPU. As it's an i5 without hyper threading and you have a z170 board it is an option, but only if you have the right BIOS version etc.