Overclocking
Nvidia's partners are doing a good enough job of pushing the GTX 770 further and beyond reference, so how much extra headroom does that leave you? Not a great deal, it seems. We managed to add an extra 45MHz to our core, but going up to 50MHz was enough to introduce problems. The memory can go higher, but we measured little gains at higher speeds.
With our core and memory overclocks in place, the GTX 770 AMP! Edition finally manages to sneak ahead of the stock-clocked GTX 780.