Basics GPUs Graphics Reviews

Making the Radeon RX 5700 and RX 5700 XT more energy-efficient and significantly quieter with the MorePowerTool | Tutorial

Powercolor showed us the way with the Silent-BIOS, today we follow with a tutorial for everyone that is suitable for everyday use: no more BIOS flashing and no more Wattman tricks, but a comprehensible manual that is easy to implement with our free MorePowerTool...

Voltage Specifications

First we start with the two voltages that we can change with the tool. With “Maximum Voltage GFX” you could set the limiter value. This value not only limits the maximum and minimum adjustable GPU voltage “Vcore” in Wattman, but Powertune also locks the voltages extremely restrictively to this value, if we measure the applied voltage once e.g. in a real game. The whole thing also goes downwards, but you quickly risk useless instabilities if you experiment below 750 mV.

 

To understand how hard the limiter for the GFX Voltage works, let’s take a look at the example with the Powercolor RX 5700 XT and the 220-watts BIOS against the 180-watts BIOS. While with the OC BIOS the limiter has to regulate constantly, with the Silent BIOS this high value is rarely reached. A lowering of this voltage would be possible, but it costs a lot of gaming performance and has a negative effect on the frametime variants.

But what you can lower without hesitation is the voltage for the SoC. The 1.2 volts of the reference card are not necessary and so the board partners also switch to working with only 1050 mV for their cards. I have also tested with 1 Volt, but there is no power saving or lower temperature measurable. Especially since the SoC with its few watts is not a big item anyway.

Reduction of power consumption

Now it becomes interesting, because we have to consider a limiter value in Watts (Power Limit) and two partial values in Amperes for the maximum currents (TDC) and adjust them if necessary. Since the arbitrator of Powertune considers average values over a longer interval, limiting the power limits for the GPU is a good way to use telemetry for our own purposes. For this, the firmware communicates with the PWM controller and queries the voltages and currents at very short intervals in order to derive a power consumption value for the entire GPU (without memory controller and auxiliary voltages!) as a product of the whole from VDDC or VSoC and the respective currents.

This is what is commonly referred to as ASIC power, but not exactly the core, because unfortunately not all loads within the GPU package are really captured. The voltage regulators of all auxiliary voltages and also MVDD and VDDCI (memory controllers) are not competing here. But it is an important value. I experimented with many values between 170 and 200 watts for the RX 5700 XT and ended up like AMD for the “reference” card at 180 watts as a compromise between power consumption and performance (sweet spot). With the smaller RX 5700, you can go down to 140 or 150 watts, depending on the chip size. But the voltages are the same. Only the board partners have released the XT up to 220 watts, which is reflected in a real explosion at the socket.

 

Let us now move on to the current limits. AMD has set this value to 170 Amps, which makes technical sense. For example, the MSI Evoke comes with 174 Amps, which increases the temperature but doesn’t help at all. Those with cooling problems can test the RX 5700 as well as the RX 5700 XT to lower the maximum current by 5 Amps each. This is especially useful if the chip has a very high quality. If the current is lowered, the card can often call up higher voltages within the voltage limits specified above in order to reach the specified power value. Only the currents heat up the card and not the voltages. The better the chip, the cooler the card. Here you can play around for a long time to find your personal optimum.

The TDC limit of the SoC should be left untouched. If you have thermal problems (hotspot), you could raise the SoC voltage (see previous page) back to 1.2 Volts and lower the default to a maximum of 12 Amps (RX 5700 10 Amps). But here you will have to keep an eye on the stability under longer full load. However, both current settings are also an interesting possibility to generate less waste heat.

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About the author

Igor Wallossek

Editor-in-chief and name-giver of igor'sLAB as the content successor of Tom's Hardware Germany, whose license was returned in June 2019 in order to better meet the qualitative demands of web content and challenges of new media such as YouTube with its own channel.

Computer nerd since 1983, audio freak since 1979 and pretty much open to anything with a plug or battery for over 50 years.

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