I have just stuck an old card that I had in my computer to see how much increase in mining speed I would get.
I had a PC with a GeForce GTX 1080Ti in and had a couple of GTX 970 cards lying around so I installed one in the computer.
Using the Claymore miner in single mode with just the 1080Ti I was getting around 30 Mh/s With the new card installed I get around 34 - 35 Mh/s on the 1080i (weird that has got faster) but only 3 Mh/s on the 970.
According to this page the 970 should get around 15 Mh/s
Does anyone have any ideas as to why the second card is running so slow?
I am thinking that for only 3 Mh/s it's probably not worth the extra power and heat buildup.