What is your config for the 4gb bro' ?
Yacoin Configs:
GTX 760 2gb (1293mhz clock, ~3.8 khash/s): -b 32768 -i 0 -L 3 -l k30x6 -H 1
GTX 760 4gb (1293mhz clock, ~4.1 khash/s): -b 32768 -i 0 -L 3 -l k95x2 -H 1 -C 1 -m 1
I get the occasional validation error but it's maybe 0.1% of the time, and I'm running the monitor off of the iGPU.
My CPU seems to be taking a beating when I'm running both cards vs just one. I don't think it should be with a 4770K...