nscrypt is way too stressful on videocards.
You're running your card inside your PC case, and at stock voltage? What brand and model is it? What clocks do you use?
Also post the commandline you're using.
stock voltage evga sc 750ti and on oc and regular, with cudaminer
when i run them in my main build they run fine but in the recent build i made they just dont seem to work at all
it doesnt run at all, like i said it goes into insta crash or insta fail