"cc miner has stopped working"
What CPU have you got?
G3900 Skylake Celeron
Try adding -d 0,1
This way you'll limit the usage to only two of your 8 1070s
Now read you CPU usage.
Your CPU has only two Cores with 1 thread each...thus each thread goes to a GPU=> two max GPUs
so I can only run 2 GPUs? that doesnt sound right.
You can run how many you wish, but with such a CPU don't expect miracles. Anyway do the test with the added option as suggested and please report back CPU usage.
With so many GPU to handle, Xeon CPU and proper OS are called into duty
Just tried this same CPU usage using 2 GPUs.