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Temperatures, Clock Rates & Overclocking
Overclocking & Undervolting
Conventional overclocking through a higher power limit and more aggressive clock rate is a dead-end. Brute force just isn't the answer. Because Gigabyte had to follow AMD's guidelines, this implementation is already running at its limit. Sure, you could dial in higher fan speeds to cool things down, creating more noise in the process, but who really wants that? As we explained in AMD RX Vega 64: The Tom's Hardware Liquid Cooled Edition, even with higher frequencies and brutal power adjustments, it is almost impossible to get Radeon RX Vega running much faster. Instead, undervolting can achieve far better results.
First and foremost, the use of a suitable utility like OverdriveNTool works wonders. As always, though, your results will also depend on the quality of your GPU. We can't generalize; you'll have to compare your improvements to ours.
Temperatures & Frequencies
We’re using the GPU temperature value exclusively because that's what our test sample’s telemetry reports. Of course, the hot-spot temperature is a lot higher. Why? You can read all about in Does Undervolting Improve Radeon RX Vega 64's Efficiency? On Gigabyte's Radeon RX Vega 64 Gaming OC 8G, those readings are up to 15°C higher. But they never hit a level that could cause problems.
The following table shows a comparison of start and end values for temperatures and GPU (boost) frequencies. Just keep in mind that these clock rates can be considerably higher in games with significantly lower loads. For example, Wolfenstein 2's indoor environments might push the card to 1.5 GHz, only to knock it way down once you step outside.
| Header Cell - Column 0 | Initial Value | Final Value |
|---|---|---|
| Open Test Bench | ||
| GPU Temperature | 42°C | 74-75°C |
| GPU Clock Rate | 1449 MHz | 1352 MHz |
| Ambient Temperature | 22°C | 22°C |
| Closed Case | ||
| GPU Temperature | 43°C | 74-75°C |
| GPU Clock Rate | 1433 MHz | 1338 MHz |
| Air Temperature in Case | 24°C | 47°C |
Temperature vs. Frequency
To better illustrate our findings, we plotted temperatures and frequencies during our sample's 15-minute warm-up phase:
Frequencies in the gaming loop are about 100 MHz higher than what we measured from AMD's reference card. This average increase of ~10% results in 40W-higher power consumption, or a roughly 18% increase. But the frame rates only go up by 5-7%, which is not a good trade-off at all.
The results of our stress test look similar:
IR Image Analysis Of The Board's Back
To round out this section, we take a look at board temperatures across several different load levels. To keep the test setup as real-world as possible, we drilled a couple of small holes through the backplate at the points relevant to our IR measurements, and then cut out the thermal pads where necessary. Since the diameter of these holes is very small, they have no significant impact on the cooler's performance.
Gaming
It's easy to see that the card is already at its limits during our The Witcher 3 benchmark. As long as you operate the Radeon RX Vega 64 Gaming OC 8G vertically on an open test bench, all values seem to be acceptable. But this may change quickly if the card is installed in a closed case instead.
Interestingly, balance between the individual voltage converters seems a bit better-optimized than Gigabyte's Radeon RX Vega 56 Gaming OC.
Once we popped Gigabyte's board into a closed case, we measured up to 2°C-higher temperatures at the voltage converters. It seems as though the fans only respond to GPU temperature, unfortunately. Even a slightly higher rotational speed would have dropped the temperatures by three or four degrees without becoming unpleasantly loud. To its credit, Gigabyte did act on our recommendations, imposing a 100 RPM-higher fan speed in its latest BIOS.
Stress Test
The stress test reflects slightly lower power consumption than our gaming benchmark. However, certain components (like the voltage converters) still get a little warmer. This is ultimately the result of a more constant load, which can be difficult to keep up with.
Even in a closed case, temperatures don't increase by more than a couple of degrees.
Throughout all four of our test cases, the voltage converters run a little cooler than what we measured from Gigabyte's Radeon RX Vega 56 Gaming OC, which operates well beyond its sweet spot.
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