There is most likely no witchcraft involved, even if you measured correctly and temps stay the same for both scenarios (normal and faster case fan speeds).
First, some questions:
What temps do you get in both scenarios for CPU and GPU? Do you use an AIO or an air cooling solution for your CPU? You do not apply a water cooling solution for the GPU, I assume!? Also, do you use a GPU or CPU centric workload to measure temps (or both)? What apps/games do you use to measure temp. And how do you measure.
Here is the reason for all those questions:
1. There is a limit for your lower temp treshold as your heatsinks works on a temperature differential. The ambient temperature has much more impact than your fan speed unless your case fans are on very low or zero rpm modes. So, if your case temp is basically comparable to your ambient temps you can increase the fan speed how much you want, you are as low as you can get it and temps will stay where they are.
2. Use sustained workloads, to get a better picture, because some workloads are too short, stuff needs to actually warm up and fan curves are at place. Also keep in mind, software measurement by sensors is not the best way to accurately measure heat in the case. Use a point and shoot thermometer gun, they provide better and more accurate temperature readings.
3. GPU temps: The lower and possibly middle front fan intakes push air to the GPU. But your GPU Fans operate independently, so even if there is more air available due to the faster fan speed, but not more cooler air per se, the GPU temps will stay very much the same in GPU load situations. Also most modern GPUs have a semi-passive cooling enabled, so even if the GPU load is increasing more air will have no measurable effect if a certain treshhold in the GPU fan curve is not passed. Hence my question if you test GPU or CPU centric. Also, is the GPU load at 100% or not? If not, you are basically not testing for GPU temps and faster case fan speeds will get you nowhere, because the GPU is not a full load.
4. CPU temps: You did not mention your CPU cooling type. If you use, let's say an 360 AIO, any additional volumes of air around the CPU will do almost nothing to the plain CPU temps, because the AIO will take care of most of that. More air will of course lower tems for VRM and possibly m.2 temps, but the CPU load temps will stay comparable for both case fan scenarios.
If you cool your CPU by air more air should obviously have some effect. BUT even then temps can stay the same if you just shovel more of the same ambient air into the case! If more air is available, your CPU fans don't need to work that hard. This is especially the case if you just push more air of the same ambient temperature into the case, but not cooler air. Also, is the CPU load at 100% in your tests?
5. Fan curves and normalized tests: You need to measure against normalized fan speeds for the CPU and GPU to actually understand the impact of the increased fan speeds. Deactivate fan curves, use fixed speeds on CPU and GPU fans and measure for both scenarios again - with sustained workloads on CPU and GPU, of course.
Hope, this helps a bit.
, but i want to learn more about airflow, i'm instrested in the replies, thank you, have a good day.
