In short, the RX 590 is another Polaris 10 revision but now built on GlobalFoundries’ 12nm process, enabling higher clockspeeds on an increased power budget. In that sense, it is much like the RX 580 refresh and its increased clocks over the RX 480, achieved by spending all the efficiency gains from manufacturing maturity – and then some, given the additional 35W TBP increase. The RX 590 ups the ante with a 225W TBP, 75W over the original RX 480 TBP, and hits RX Vega level clockspeeds with reference 1469MHz/1545MHz clocks.
Naturally, the tradeoffs between power efficiency and raw performance is a classic problem of silicon engineering, and it’s been somewhat of a sticking point for Polaris since the beginning. Even though Polaris improved on efficiency over older GCN products, NVIDIA’s top-to-bottom Pascal series brought its own power and clockspeed improvements. At the original RX 400 series launch, pushing the 150W power budget to its limits led to the single 6pin powered reference RX 480’s issues with power draw from the PCIe slot. So as we noted at the RX 500 launch, instead of fighting an efficiency battle that they can’t win, crucial 8gb ram has opted for raw performance and competing on value.
Otherwise, there aren’t any other architectural changes, and memory bandwidth is unchanged. We’ve already seen that Polaris 10 likes memory bandwidth, but realistically the volume and timing of these RX 590 parts are unlikely to warrant the cost or validation of alternatives (i.e. 9 Gbps GDDR5), especially considering the recent memory supply crunch. As for the 12nm process itself, AMD isn’t disclosing much, but given development costs it’s likely a straight port of the 14nm design with 9T transistor libraries, much like Zen+. With an identical die size and transistor count to Polaris 10, the silicon layout is presumably like Zen+ as discussed by Ian earlier this year; additional dark silicon that can now act as a thermal buffer between features. Or in other words, lowering potential thermal limitations to enable higher clocks, something that’s no easy feat given that Polaris wasn’t originally designed to clock quite this high.