It's been an exciting couple of weeks in the short life of the Radeon RX 480. AMD's new graphics card is the first to use the next-generation Polaris 10 GPU, hot off the fabs. Unfortunately, not all of the excitement has been positive. Shortly after launch, the good people over at Tom's Hardware and PC Perspective did some deep-diving on the new card's power draw. The sites found that the card exceeded the specification for amperage drawn from the PCIe slot. This news ended up being a big concern for some potential RX 480 buyers.
In response, AMD released a statement saying that it didn't think the 480's excessive power draw was a threat to motherboards or other components in a system. Nevertheless, the company pushed out a new driver—Radeon Software 16.7.1—that re-balanced the board's power draw, allowing it to pull more power from the PCIe 6-pin connector rather than the PCIe slot. The company also included a new option in the updated driver that would prevent the card from drawing quite as much juice in total for users who were particularly concerned about their systems. This "Compatibility Mode" can be toggled on and off in the Radeon Settings software, and it simply lowers the board's power target. AMD is shipping the driver with this feature turned off by default.
Of course, making such low-level tweaks to the way the Radeon RX 480 works raised questions about how the card will perform post-update. Now that we've had some time with the new drivers and the new compatibility mode option we can give a clearer picture of the effect of this driver update on the games we tested. In the interest of time, we didn't run our whole suite of benchmarks again. For the games that we did retest, we used the same set of settings and procedures that we used in our primary RX 480 review. We chose two games—Grand Theft Auto V and Crysis 3—to put back through the wringer, since they were both fairly playable at our test settings.
Crysis 3 revisited
We'll start with Crysis 3 today, since it's both a performance test and the benchmark we use to generate our power-use numbers. Crysis 3 is also a potentially interesting test because it's an older game that AMD isn't likely to have released any specific optimizations for. As we noted, we used the same graphics settings, the same benchmark run, and the same processing methods as we did in our full RX 480 review. We compared the results from our initial test
Our average FPS numbers look good. No news here. Most importantly, there's barely any change in performance between the release driver for the card and the Radeon Software 16.7.1 update. While the new driver does appear to increase performance slightly, these are averages of hand-run benchmarks, so the results are probably well within any margin of error. As always, we don't put all that much stock in pure-FPS measures since they don't show the whole picture of graphics performance.
Our frame-time graphs are a bit crowded, but they basically tell us the tale we want to see. Performance between the release driver and the 16.7.1 update is largely the same. Turning on Compatibility Mode does cause our card to display a couple large spikes that could affect perceived smoothness, but that's unsurprising since we're probably reducing its power budget—and, hence, performance—somewhat.
These "time spent beyond X" graphs are measures of "badness"—the amount of time that a card was displaying animation that may have been less than fluid, or at least less than perfect, during our test. If frames are taking longer than 33.3ms to render, the frame rate will drop below 30 FPS. In those cases, we expect to have some judder and other ugliness with vsync enabled on a 60-Hz monitor.
The new driver performs admirably here, although we still see a small increase in the amount of time spent beyond both 16.7 and 8.3ms. The compatibility driver fares a bit worse, with an almost doubling of the time spent beyond the key 16.7ms. This isn't surprising, given the lower power use, and it also does a good job of demonstrating exactly how sensitive these frame-time measurements are.