AMD now offers new Radeon Software Crimson Edition version 16.7.1 drivers for AMD accelerators. Two of the three notes they highlight relate to fixes for the issues that could cause RX 480 graphics cards to draw excessive power:

Radeon Software Crimson Edition 16.7.1 Highlights

• The Radeon™ RX 480’s power distribution has been improved for AMD reference boards, lowering the current drawn from the PCIe bus.
• A new “compatibility mode” UI toggle has been made available in the Global Settings menu of Radeon Settings. This option is designed to reduce total power with minimal performance impact if end users experience any further issues. This toggle is “off” by default.
• Performance improvements for the Polaris architecture that yield performance uplifts in popular game titles of up to 3% [1]. These optimizations are designed to improve the performance of the Radeon™ RX 480, and should substantially offset the performance impact for users who choose to activate the "compatibility" toggle.