While generally well received, one of the sour issues of the Radeon RX 480 is that it draws a shitload of power from the PCI Express motherboard slot. Reviewers found that on average, the card uses more power than the maximum of 75W that's allowed by the PCI Express specification.
This issue was discovered by tech review sites that do per-rail power consumption testing and it raised concerns about possible damage. Right after the launch of the RX 480, AMD said it would look into this issue and now there's an official response claiming a driver fix is coming in the near future:
As you know, we continuously tune our GPUs in order to maximize their performance within their given power envelopes and the speed of the memory interface, which in this case is an unprecedented 8Gbps for GDDR5. Recently, we identified select scenarios where the tuning of some RX 480 boards was not optimal. Fortunately, we can adjust the GPU's tuning via software in order to resolve this issue. We are already testing a driver that implements a fix, and we will provide an update to the community on our progress on Tuesday (July 5, 2016).
At this point we can only speculate but I'm looking forward to see how the fix will affect both the power consumption and the performance of the AMD Radeon RX 480.