AMD RX 480 Drawing Too Much Power and Potentially Damaging Motherboards?

AMD's new RX 480 $200 graphics card is out and delivers GTX 970/R390 performance as promised. However, there are some conflicting reports of the new Polaris GPU drawing more power from the PCI-e slot than it is rated. According to Tom's Hardware, the RX 480 draws 86 watts peak from the motherboard's PCI-e slot although the official ceiling is 75 watts.

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AMD’s Radeon RX 480 draws an average of 164W, which exceeds the company's target TDP. And it gets worse. The load distribution works out in a way that has the card draw 86W through the motherboard’s PCIe slot. Not only does this exceed the 75W ceiling we typically associate with a 16-lane slot, but that 75W limit covers several rails combined and not just this one interface.

 

 

With peaks of up to 155W, we have to be thankful they're brief, and not putting the motherboard in any immediate danger. However, the audio subsystems on cheaper platforms will have a hard time dealing with them. This means that the "you can hear what you see" effect will be in full force during load changes; activities like scrolling may very well result in audible artifacts.

 

After Tom's Hardware published their report, other websites such as PCPer followed up with their own testing and reported similar findings: 

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The results are compelling: at stock settings the RX 480 is 160+ watts on average and spikes to 170 watts several times.

 

 

Metro: Last Light (4K) power draw, RX 480, Click to Enlarge

Taking a closer look reveals that the motherboard PCI Express connection is supplying 80-84 watts of power over the +12V rail continuously, while the +3.3V rail hovers just below 5 watts. This is definitely a concern for the RX 480 design, but to what degree?

 

Additionally, there are some users that reported potential issues with their motherboards that arose after using the RX 480 in their systems:

Keep in mind both of those reports do not 100% confirm the problem is the RX 480 but given the reported issues with it's power draw and these users boards experiencing problems after installing an RX 480, there is a strong possibility that it is the cause.

There is a reddit thread in r/AMD on this topic and AMD's Robert Hallock has issued the following response:

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1) The RX 480 meets the bar for PCIe compliance testing with PCI-SIG. //edit: and interop with PCI Express. This is not just our internal testing. I think that should be made very clear. Obviously there are a few GPUs exhibiting anomalous behavior, and we've been in touch with these reviewers for a few days to better understand their test configurations to see how this could be possible.

2) Update #2 made by the OP is confused. There is a difference between ASIC power, which is what ONLY THE GPU CONSUMES (110W), and total graphics power (TGP), which is what the entire graphics card uses (150W). There has been no change in the spec, so I would ask that incorrect information stop being disseminated as "fact."

We will have more on this topic soon as we investigate, but it's worth reminding people that only a very small number of hundreds of RX 480 reviews worldwide encountered this issue. Clearly that makes it aberrant, rather than the rule, and we're working to get that number down to zero.

/edit for absolute factual clarity.

 

We're awaiting AMD's full official response which should hopefully be coming soon. 

UPDATE: TechPowerUp contacted AMD and received the following official response:

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"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 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)."