For our manual overclocking tests, we used MSI Afterburner. Our best results are as below.
Interestingly, Palit only allows the power limit to be increased up to 104%, so it cannot be increased above 255W. We were still able to add 170MHz to the GPU core and 1500MHz to the memory while overclocking.
This overclock saw real-world clock speed average 2894MHz, which is slightly slower than what we managed with the Founders and Aero OC cards.
We still saw acceptable frame rate increases as a result of this overclock, in the 4-7% region depending on the game. It won't make a massive difference to your gaming experience but it may be worth it for some.
Power draw didn't change much even once overclocked, we measured just a 1W difference overclocked versus stock.