Cooling Noise and Power

For my last few tests, rather than focusing on in game performance, I like to check out other aspects of video card performance. These are also the most important ways to differentiate the performance between cards that have the same GPU. To start things off I took a look at power usage.

For this, our new test setup utilizes the Nvidia-designed PCat v2 along with cables to handle both traditional 6 or 8-pin connections as well as the new 12VHPWR. The PCat also utilizes a PCIe adapter to measure any power going to the card through the PCIe slot so we can measure the video card wattage exclusively, not the entire system as we have done in the past. I test with a mix of applications to get both in game, synthetic benchmarks, and other workloads like Blender and AIDA64. Then everything is averaged together for our result. I also have the individual results for this specific card and I document the peak wattage result as well which is almost always Time Spy Extreme. The Hellhound RX 7900 XTX averaged 434 watts across all of the tests and peaked at 478 watts. The average puts it up near the top of the charts with just the RTX 3090 Ti and RX 6950 XT from last generation ahead of it. This is 32 watts above the reference card and was enough to jump up ahead of the RTX 4090 Founders Edition. For reference with the Hellhound RX 7900 XTX running ahead of the RTX 4080, the 4080 is farther down in the charts with an average of 310, 124 watts less than the Hellhound RX 7900 XTX. Interestingly the peak wattage for the Hellhound RX 7900 XTX was when running Watch Dogs Legion, not Time Spy which was much closer to the average.

With having exact peak wattage numbers when running Time Spy Extreme I was also able to put together a graph showing the total score for each watt that a card draws which gives us an interesting look at overall power efficiency in the popular and demanding benchmark. The Hellhound RX 7900 XTX came in at 33.34 points per watt which was slightly more efficient than the reference RX 7900 XTX. This put it below the RTX 4070 Founders Editon as well as the 4080 and 4090 which are a lot more efficient with their lower wattages.

My next round of tests were looking at noise levels. These are especially important to me because I can’t stand to listen to my PC whirling. Especially when I’m not in game and other applications are using the GPU. For my testing, though I first tested with the fan cranked up to 100% to get an idea of how loud it can get, then again at 50% to get an idea of its range. The Hellhound RX 7900 XTX ran in the bottom 1/3 of the 50% chart at 39.1 db but was just above the midpoint once the fans were cranked up to 100%. The three-fan setup ran the fans at 3383 RPM which does put the 100% fan noise a little higher in the noise chart than in the RPM chart.

I also take a look at noise performance while under load. For that when running AIDA64’s stress test I wait until the temperature of the card has leveled off and then measure how loud things are when the card is at its worst-case scenario with the stock fan profile. Here the Hellhound RX 7900 XTX came in at 36.3 db which is really impressive for a triple fan card, especially such a high-end model. When under load the Hellhound RX 7900 XTX had its rans running at 42% which helped with the load noise levels as well.

To finish up my testing I of course had to check out the cooling performance. To do this I ran two different tests. I used AIDA64’s Stress Test run for a half-hour each to warm things up. Then I documented what temperature the GPU leveled out at with the stock fan profile and then again with the fans cranked up to 100%. With the stock profile, the Hellhound RX 7900 XTX leveled off at 65c on the GPU temps but the GPU hotspot was still way up there at 94c. This was 4c lower than the reference card which wasn’t as big of a gap as I expected. Cranking the fan speed up, however, dropped that down to 49c which was 10c lower than the reference card. The Hellhound RX 7900 XTX had a 16c delta between the stock fan profile and the 100% fan speed showing just how much room is still left in the cooler. They just have a fan profile that is focused more on keeping things quiet. At 100% fan speed the GPU hotspot did drop down significantly which is a big improvement over our reference card that has the GPU hotspot issue and is always running hot.  

While running the stock fan profile testing I also took the time to get a few thermal images so we could see what is going on. The fan side of the Hellhound RX 7900 XTX is running cool across the entire card with the hottest spot being the bottom half of the far left fan at 39c, but that isn’t too far off from the far end of the card running at 30c. You can see most of the heat is up on the top where a majority of the air is pushed out as well as with the exposed open area in the middle where you get a full view of the OCB as well as the heatpipes right when they leave from over top of the GPU. The backplate does a good job of spreading the heat around except for the exposed back of the GPU which is by far the hottest spot on the card at 72c.