I have the same with gtx 1070. Didn't try other cryptonight coins though, but with ETH temp and fans go crazy :D I trace gpu behavior with GPU-Z and MSI afterburner. Although the GPU Load is 100% (after some tweaking) average power consumption is 50-55% TDP. I suppouse we should be happy, that makes monero mining more profitable, doesn't it?

It is most probably because you are using the standard settings (which is as far as i remember 40 blocks and 8 threads). What you can do is to change these settings (see the ccminer readme file). What I am usually doing when using a new graphics card for mining is I am creating an excel sheet with the following collums: blocks | threads | hashes per second min. | hashes per second max. | gpu load | memory usage | mean of hashes per second within 5-10 minutes | standard deviation of hashes per second within 5-10 minutes. for gpu load and memory usage you can use tools like gpuz (windows). what you wanna do is to vary threads and blocks in order to maximize your gpu load to 98-100% without going to high with your specific memory usage (in your case 2gb) but also try to get high hashrates without letting them jump too much up and down (high mean, low standard deviation). so the next step could be to try 8 threads and 48 blocks for example.