To answer some upthread questions, yes I'm running my nist5 on Nvidia, so SGminer wasn't doing so hot.
As far as I can tell I'm using a nist5 optimized CC miner, but it's really hard to figure out versioning of those two programs (SG/CC) because google is very outdated typically and there doesn't seem to be a single good repository of info of version history and specialized forks.
For those trying to get SG/CC/Sph working, make sure you're using the right "algo" command line argument. Some use -k, some use -a or -algo, others don't need it if they only support a single algo and/or auto-detect the algo from the stratum server.
Correct, SGminer doesn't seem to do well on Nvidia cards for the moment.
The recommended version of CCminer is tpruvot's v2.0 w/CUDA 8, released here:
https://github.com/tpruvot/ccminer/releases UNLESS you have an older card with only CUDA 7.5 support (e.g. my old GTX760, which only worked with v1.6.4).