I am expecting a roughly 20/30% increase in rendering power across the board, going to 40% in some cases. In lightly threaded workloads you could even see a bigger increase because of the advanced turbo on the 4770k CPU. Also the switch to a 87 motherboard will bring you a lot of new features. Most notable is support for higher MHz RAM, USB3, 6Gb/s SATA and more PCIe 3 lanes. Also by putting a good cooling you can extend the Turbo duration of the CPU yielding even more performance gains or as 2nd option - overclock. Another notable plus of the move to the Haswell CPU is the lower overall power consumption of the platform.