I didn't do a lot of testing but with stock voltage you should reach a GPU clock around 1900 to 1950mhz and with 0.862V I was able to get 1750mhz stable. So yeah around 150 to 200mhz lower GPU clock...but fortunately you can still overclock the memory clock even with the lower voltage. I happily accept this little loss of performance in favor of lower temps and noise.