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AMD Radeon RX 480 exceeds PCIe power limit

Reviews indicate overclocked RX 480 fails to stick with PCIe specification

Certain reviews indicate that an overclocked AMD Radeon RX 480 draws exceeds PCIe power limitation. Typically the PCIe x16 slot is designed for up to 75 watts. But with the RX 480 overclocked by 3.5%, the power draw via PCIe slot is crossing 95 watts. The card is also crossing the 100-watt barrier from its six-pin PCIe power connector as well.

The maximum draw is 80-85 watts via +12v rail and 4.5-5.0 watts via 3.3v rail. These are a consistent power draw and not peak.

The extra power draw from the six-pin PCIe cable might not a concern for a good enough power supply. But drawing such consistent power from the slot is a concern. While certain peaks are unlikely to damage the motherboard, consistent power drain excess may damage its traces in the long term.

Potential concern with existing hardware

Ryan Shrout explains in the most simple way possible:

I asked around our friends in the motherboard business for some feedback on this issue – is it something that users should be concerned about or are modern day motherboards built to handle this type of variance? One vendor told me directly that while spikes as high as 95 watts of power draw through the PCIE connection are tolerated without issue, sustained power draw at that kind of level would likely cause damage. The pins and connectors are the most likely failure points – he didn’t seem concerned about the traces on the board as they had enough copper in the power plane to withstand the current.

As we all know with hardware failures in PCs, this is something that could in theory happen during a single gaming session, or it might instead take months and months of gaming to wear down componentry. Or it might never affect your system at all. I tend to lean on the side of worrying less about this power draw concern than many in the community are pushing me to. Following the likes of ASUS, MSI and Gigabyte over the last 5-10 years, I have seen all the major motherboard vendors focus on quality of componentry, and specifically on power delivery, in a wide range of product families.

That doesn’t mean that any one particular motherboard is not prepared for the overclocked power draw on a Radeon RX 480, or that lower cost or older motherboards that some gamers are still using in their PCs might not be built to withstand it. We just don’t know yet; not enough hardware is in enough hands.

AMD addresses the concern

Meanwhile, Raja Koduri addressed this when it was the first question asked during his Reddit AMA:

Great question and I am really glad you asked.

We have extensive testing internally on our PCIE compliance and RX480 passed our testing. However we have received feedback from some of the reviewers on high current observed on PCIE in some cases. We are looking into these scenarios as we speak and reproduce these scenarios internally. Our engineering team is fully engaged.

Most likely, there might be a software patch. It is also hoped that the fix wouldn’t affect its performance. AMD could have simply used an 8-pin PCIe connector instead viz. recommended for up to 150w power draw. There’s also an issue where people will assume the power draw is high due to the eight-pin PCIe connector. Hopefully, its AIC partners would implement this with their non-reference/ factory overclocked designs. In any case, potential risk on the user’s existing investment is not really something anyone will appreciate, and create a bigger issue. The RX 480 non-reference designs with extra 8-pin PCIe connector might elevate the issue.

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