How to use AMD's WattMan, the powerful new overclocking tool for Radeon graphics cards
One of the $200 Radeon RX 480’s biggest headlining features is actually a new Radeon Crimson overclocking tool dubbed Radeon WattMan. The ability to overclock your Radeon card with AMD-supplied software isn’t completely new: Prior to WattMan, AMD offered its less robust OverDrive tool since about 2007. (Older Radeon graphics cards still default to OverDrive, even if you install the latest Radeon Crimson software.)
But while OverDrive offered control over clock speeds, the PowerTune limit, target temperatures, and fan speeds, it used a rather limited slider-based interface. Additionally, OverDrive’s controls weren’t very granular and lacked important features like core and memory voltage control, individual clock state control, and real-time graphing of all of these performance variables. These issues forced most overclockers to turn to robust third-party software like MSI’s Afterburner and EVGA’s Precision X instead.
But AMD’s Radeon WattMan remedies all of these shortcomings. Here’s how to use it.
Working with WattMan is dead simple. Open up AMD’s Radeon Settings app and click the Gaming tab, then Global Settings, and finally the Global WattMan tab. You’ll be greeted by the interface shown below.
WattMan’s most striking feature revolves around its real-time graphing, dubbed “Histogram,” which maps out your RX 480’s activity level, current core clock speed, memory frequency, temperature, and fan speed. In other words, every crucial measurement you need to monitor while overclocking your graphics card.
Best of all, if you see something weird on the graph—like a big clock speed drop—hovering your mouse over the issue will bring up the stats for that specific point in time. If you’re trying to troubleshoot a cooling or performance problem, WattMan’s graphing feature is a godsend.
A thoughtful twist on this performance-tracking feature is the ability to use it globally or with only specific applications. AMD’s per-app Profile settings allow you to use WattMan to profile performance while a specific game is running for up to 20 minutes at a time. Select the game you want to profile, enable the Histogram option for it, and WattMan will begin recording when you launch the game.
This application-specific profiling ties in nicely with the rest of WattMan’s overclocking capabilities, which can also be applied on a per-game basis. With the Profile WattMan tools located inside each game’s specific settings in Radeon Crimson, you can overclock your RX 480 in the games that need more horsepower and bump the target temperature down in less strenuous titles.
WattMan’s powerful granularity is the application’s biggest strength, and that strength is most apparent in its clock speed and voltage controls.
Like the power management technology found on modern CPUs, AMD’s PowerTune management engine switches between seven performance states, which are defined by unique clock speeds and voltages. Using the WattMan tool you can configure each of these seven states to your own personal preference.
For most people, that means overclocking the top clock state into the highest possible stable speed, up from the RX 480’s normal 1,266Mhz boost state. But before you do that, you’ll want to increase the card’s power limit as much as possible.
The power limit slider dictates the amount of power that your graphics card will allow itself to draw. If you increase it, you can reduce power consumption-related throttling—which can lead to higher stable overclocks—and if you decrease it you can reduce overall power consumption. During our testing, we found that the RX 480 performed slightly better if you set the PowerTune limit to +10 percent.
Theoretically the RX 480’s PowerTune limit can be raised all the way up to +50 percent (or lowered to -50 percent). But AMD engineers say that +20 to +25 percent will probably more achievable for most cards. Ah, the silicon lottery.
With that done, overclocking a graphics card involves firing up a looping benchmark like Unigine Heaven and then increasing the core clock speed of your graphic card until the benchmark crashes. Then you reduce clocks speed a bit and run it for a few hours to verify stability, continuing to reduce clock speeds if necessary. (Adjust the card’s power limit using the same technique.) We were able to push our RX 480’s clock speeds up to 1,330MHz, or about a 5 percent increase, before we ran into stability issues.
When it comes to the per-state voltage controls, it’s best to focus your efforts on the highest three clock states, where the RX 480 spends most of its time during intense gaming sessions. State 7 is the boost state of the RX 480, where the clock speed in WattMan is set to 1,265 and the voltage is set to 1,131. The maximum voltage that WattMan can set for any given state is 1,150. If you want to overclock the RX 480, setting State 7’s voltage to 1,150 will improve stability while you raise clock speeds.
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.
Finally, AMD’s WattMan lets you define the RX 480’s most noticeable characteristics. You can manually set minimum and maximum fan speeds, a minimum acoustic limit, and maximum and target temperatures.
AMD’s stock settings for all of these are actually pretty good, but you can tweak them to your heart’s content. If you’re overclocking, you’ll probably want to increase the RX 480’s target temperature by three to five degrees to reduce potential thermal throttling while the card cranks away at higher clocks.
Likewise, you’ll want raise the target fan speed from the default 2,200 revolutions per minute (RPM) maximum to ensure your RX 480 stays cool under the increased heat. But don’t take this too far, because the RX 480’s blower-style cooler sounds like a ferocious hair dryer when it’s spinning at 100 percent fan speed. Our recommendation: Set the target fan speed to 4,000rpm—it’ll be loud—and work down to an acceptable-to-you noise level from there. We found 3,000rpm to provide the best blend of acoustics and cooling.
AMD’s WattMan is a major step forward for Radeon overclocking, and a stellar in-driver tool for gamers looking to get the most out of their new RX 480 graphic cards. If you’ve picked up AMD’s new mainstream champion and haven’t played around with WattMan yet, the only thing I have to say to you is, “U Watt Man”
Because I just had to make a joke about that horrendous name.