Maybe I discovered some type of error...
After pool has solved some blocks very quickly ccminer hashrate drops radically and one of my cards stops (in this case #1)
Although one card stopped accepted hasrate is the same by ccminer. Pool hasrate drops so one card has really stopped.
Default speed, no -g, linux, 6*750ti.

http://s5.postimg.org/6dsaphgh3/ccm.jpg

I think this is only about quark algo.