Power Usage and Temperatures
For some people, performance is the only thing important, but for others, power usage and temperatures also play a role so we do take a look at both of those as well. This is especially important in SFF or even just smaller mid-sized builds and it affects the components you need to get for your system as well as your PSU and cooler. To take a look at power usage I ran three different tests. I noted the idle power draw of our entire system then I took a look at the load wattage of the system using two different workloads. One was wPrime and the second was AIDA64 using their FPU workload which is extremely demanding. At idle the testbench with the system with the three non-X CPUs in it does still have the high wattage at idle that we saw with the other 7000 Series CPUs with the 7700 sitting at 97.1 watts, the 7600 at 97.3, and the 7900 at 106 watts. But with the wPrime test, all three have significantly lower under load numbers. The 7700 and 7900 were both at 181 watts and the 7600 was a little lower at 173 watts. For comparison the 7600X pulled 193 watts in the same test, the 7700X was at 225, and the 7900X was at 226. The second graph which has the AIDA64 FPU workload does a better job of showing the clear difference with all the non-X in the 179-181 watt range. Then the 7600X is at 203, the 7700X is at 237, and the 7900X is even higher at 305 watts. All three show a huge drop in power usage but look at the gap between the 7900 and the 7900X!
The reason the non-X CPUs were exciting was because of their 65-watt TDP but while the lower power usage is nice the real reason that was important is because of the temperatures that the original 7000 Series CPUs were running at. AMD designed all of them to run at 95c at all times and .that they did. The 7700X ran at 94c in our thermal test, the 7900X was at 91C, and the 7600X was the lowest at 87c which was still hot. The 65 watts CPUs change that up significantly though and you might be surprised at the order in which they are in our graph. The Ryzen 9 7900 is the lowest of the three in our test running at 52c while under load. The 7700 ran warmer at 64c which was 30c lower than the 7700X, then the 7600 was the hottest at 79c. While they do seem to run hotter the fewer cores they have, I have to wonder if our 7600 has a worse connection with its heatspreader given how much warmer it was running but I did test this multiple times to confirm it wasn’t a thermal paste issue.