AMD promises fix for Radeon RX 480's controversial, spec-exceeding power consumption

AMD's $200 Radeon RX 480 draws much more power than it should through your motherboard, which could damage low-end systems.
  • Brad Chacos (PC World (US online))
  • 04 July, 2016 00:01

AMD engineers are putting in extra hours this holiday weekend after troubling issues arose over the Radeon RX 480’s power draw—issues that could theoretically damage lower-end motherboards in extreme circumstances.

Despite ostensibly being rated as a 150 watt card, Tom’s Hardware found that AMD’s graphics card used an average of 168W under load. Intrigued, the site employed the use of exotic test equipment to determine exactly how much power the RX 480 pulled from both the PCI-E slot in the motherboard as well as card’s six-pin power connector (which hooks directly into the power supply) and found something even more alarming: The card pulled up to a whopping 90W over the motherboard’s PCI-E slot, far exceeding the 75W maximum the slot is rated for.

German site observed identical behavior, as did TecLab.

PC Perspective performed even deeper testing shortly afterwards. It found similar results to Tom’s at baseline levels and witnessed Witcher 3 consuming over 190W of sustained power draw when the RX 480 is overclocked, with 95W of that coming via the PCI-E slot. Worse, PC Perspective discovered that AMD’s card drew 7 amps over the PCI-E slot’s +12v rail, which is rated for 5.5 amps maximum. The Radeon RX 480 also overdraws the board’s solitary 6-pin power connector, though that’s less worrisome since it’s not passing through your motherboard.

asus motherboard pcie slots Brad Chacos

The PCI-E slots on an Asus X99 Deluxe motherboard.

So what, you ask? PC Perspective spoke to anonymous motherboard vendors, who said that while 95W spikes through the PCI-E connector aren’t a big deal, sustained power levels that high could potentially fry a motherboard’s pins and connectors.

That's scary, but we can't be sure if the RX 480's spec-exceeding power draw is a serious issue in the real world yet. The major motherboard vendors have been beefing up the quality of their components for years. That said, AMD’s big push for the Radeon RX 480 is bringing premium-quality gaming to the masses. There’s a good chance the $200 graphics card will wind up in some systems with bottom-budget motherboards, which might wind up with instability or damage from the RX 480’s out-of-spec power draw.

Fortunately, AMD says a software-based fix is incoming:

“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).”

So I guess we’ll hear more on Tuesday. If the software fix involves reducing the power draw for the RX 480, that’ll most likely lower performance in the reference editions of the card as well, especially since Polaris’ performance is closely tied to the card’s power limit.

radeon rx 480 5 Brad Chacos

It's too bad that 6-pin connector on the AMD Radeon RX 480 isn't an 8-pin.

The real bummer: This all could’ve been avoided if AMD simply used an 8-pin or 2x 6-pin power connectors. I’d expect many custom RX 480s from AMD’s partners to beef up the card’s pins, both to increase the card’s overclocking potential and to completely sidestep this troubling power consumption issue.

It’s a damned shame AMD overreached with the single 6-pin connector rather than playing it safe. The Radeon RX 480 redefines what’s possible with a $200 graphics card, and indeed consumes far less power than the older R9 390/390X that it’s comparable to performance-wise. Oh well. While you’re waiting to hear more from AMD on Tuesday, I’d highly recommend reading PC Perspective’s exhaustive analysis on the RX 480’s power draw issue. It’s stellar.