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For our power, temperature, clock speed, and fan speed testing, we use Powenetics testing hardware and software. We capture in-line GPU power consumption by collecting data while looping Metro Exodus — this time at 1080p medium instead of our normal 1440p ultra, due to the VRAM limitations. We also test with the FurMark stress test at 1600x900. Our power testing PC uses an open testbed, as that's required for all the extra wires and riser card, and it's the same Core i9-9900K that we've used for the past several years.
Both FurMark and Metro Exodus basically flatline at a steady 54W power draw with the RX 6400. That's technically 1W higher than the official board power rating, but it's definitely nothing to worry about. If you're wondering, the GPU power draw (not including VRAM or the rest of the board) peaked at around 43W.
Despite using about half the power of the RX 6500 XT, clock speeds on the RX 6400 were still pretty high, averaging 2272 MHz in Metro Exodus. That dropped to 1990 MHz in FurMark, putting a much higher load on the GPU cores. You can imagine that even at a lower power limit of 15W, clock speeds and performance would still remain decent, which is basically what you get from integrated graphics solutions like the Ryzen 7 6800U.
Temperatures peaked at around 70C in both our test scenarios, with fan speeds generally holding steady at around 1250–1300 RPMs. That's not very high on the fan speed, and the fan wasn't loud by any metric, but it was still slightly audible above ambient room levels.
We measured noise levels at 10cm using an SPL (sound pressure level) meter aimed at the center of the fan. That helps to minimize the impact of the CPU cooling fans, and the noise floor (with the CPU fans running) of our test environment and equipment was <33 dB(A). The PowerColor RX 6400 reached the same ~1250 RPM after 15 minutes of gaming, with a stable noise level of just 37.3 dB(A). Just by way of reference, simply powering up my normal gaming PC six feet away from the testbed brought the room's ambient noise level up to 42 dB.
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