Uninstall ntune ASAP! nTune will do nothing but cause you frustration and cause system instability. Use ATItool or Rivatuner to OC your GPU, overclock your CPU and ram from the bios.
evga precision or ati tool FTW guys!! very simple and easy to use, although precision to my knowledge doesnt have an artifact tester whereas ati tool DOES!! rivatuner ftl...