From the review, at gaming power consumption, I'm reading 305W vs 247W, for a 58W difference. That said, the extra heat is a PITA in the summer. But frankly, it's quite awesome in the winter.
Also, someone mentioned this before, but the Gigabyte G1 RX 480 AIB is probably the worst RX 470/480 AIB on the market in terms of cooling performance. It is a whopping 8C warmer (81C vs 73C) at load compared to the MSI RX 480 AIB (considered one of the best). This is while the Gigabyte AIB runs about 90 MHz core clock lower than the MSI AIB (1303 MHz vs 1216 MHz).
If [H] reviewed the MSI AIB instead of the Gigabyte AIB, I'd expect about a 5% improvement and 8C lower load temperature, at around the same power consumption.
http://www.guru3d.com/articles_pages/msi_radeon_rx_480_gaming_x_review,6.html
http://www.guru3d.com/articles_pages/gigabyte_radeon_rx_480_g1_gaming_review,6.html