Run a benchmark in game you'll get a more accurate result. There could be a bug with GPU-Z. Unless it's properly monitored for you in the past though it's still up in the air given the overclocking issue with these drivers. I'd run a raw benchmark comparison to get a definitive answer. On an unrelated note, it's possible that Nvidia is in the process of uploading new drivers as the searching function on Nvidia's site is currently borked depending on which card you select. They could be updating... keep your fingers crossed.