So now you know how to overclock the Radeon RX 480, and what to expect when using the tools. But WattMan tinkering with the goal of improving power efficiency shouldn’t be overlooked, especially given the unorthodox power consumption of RX 480 reference cards.
Merely setting the PowerTune limit to -20 percent transforms the RX 480 into a significantly more efficient graphics card, with only a tiny hit to performance, as I detailed in an examination of the RX 480’s power usage at SemiAccurate.
If you want to go further, “under-volting” is performed using a very similar process to overclocking, but instead of playing with clock speeds to increase performance, you decrease the voltages required to maintain stability at stock clock speeds. AMD’s WattMan makes this easy. But before we dig in, make sure that you have the Voltage Control toggle for both the GPU and the Memory in the Manual control position. If these aren’t both in Manual mode, your voltage adjustments won’t have any effect, in a bizarre WattMan quirk.
The process for under-volting once again involves opening up a looping benchmark and letting it run while you incrementally reduce voltages. Eventually you’ll lower voltages too far and the benchmark will crash. Increase your RX 480’s voltages slightly from that point and then run the benchmark a few hours to verify stability. In our testing we were able to lower voltages for the top 3 states down to 1050 millivolts (mV) while maintaining stock clock speeds, which is an 81 mV savings over the default settings.
Radeon Crimson’s Frame Rate Target Control (FRTC) feature can also help you to save even more power by capping the maximum framerate of you GPU, so your graphics card won’t pump out more frames than your monitor can display. Why let your GPU render frames you’ll never see? Take the power savings instead.
With a power-sipping under-volt or perhaps even a bit of an overclock applied, we can now turn to tuning the RX 480’s card’s memory. Cranking up memory clocks can help increase performance.
AMD’s WattMan again provides granular control over the RX 480’s onboard RAM, with the ability to over-volt the RX 480’s GDDR5 by up to 150 mVs and raise clock speeds from 2,000MHz up to 2,250MHz. We were able to hit a stable memory overclock of 2,200MHz, or a 10 percent overclock, after manually raising the voltage to 1,150 mV.
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