AMD just issued a small statement on the PCI-Express over-current Issues mentioned and reported on the web. It seems that the Radeon RX 480 reference cards are going over spec using more than 75 Watts over the PCI-Express slot and then another 75 Watt over the 6-pin power connector. If you pull over 75 Watts from the motherboard slot, it will place more strain on it and some motherboards might note cope with that very well. To that end and to solve the issues reported they will address this issue in software. The cards do exceed 150 Watts, in fact we measured it at 166 Watts. Here is that statement:
"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 8 Gbps 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)."
If this is fixed by software (driver) this likely means it will be throttling down if it hits a certain power state, so if a higher than 150 Watt power state is reached, AMD might be throttling down the cards in the future to meet the proper P state. Yesterday we have been performing some additional stress tests ourselves and cannot replicate the issues mention on the web. We do see a minor increase of temperature on the PCI-Express slot, but nothing rather concerning. Yesterday we updated the FLIR images in our reference review to show that.
منبع: http://www.guru3d.com/