Relevance vs. Waste heat – Which CPU is best?
I did a lot of tests in advance with a wide variety of air and water coolers to find out where and how you can reliably measure even the finest nuances in the different cooling performance. This certainly doesn't sound very complicated, but it is, because it is not only the different heatspreader sizes and power losses that distinguish the CPUs from each other. If you want to test air and water coolers reliably on a single system, you have to be able to produce precisely graduated power of power (heat). Since I would like to use precisely set values of 65, 95, 125, 155, 185,215 and 245 watts, I need a suitable, powerful CPU and a correspondingly calibrated motherboard, where I can also adjust the supplied power as precisely as possible.
Since I was able to withe the Alphacool polar bear Aurora also the 250 watts of a Core i9-7980XE still very safe and with a large cushion, I deliberately chose this CPU, although Intel's TIM instead of the Indium lot in contrast to the Core i9-9980XE measurable disadvantages Offers. Nevertheless (or just because of this) this Socket 2066 CPU is particularly suitable, because if I wanted the ideal case, it would have become a power MOSFET with smart control. But this has zero practical relevance. A Core i9-9900K does not easily create the 250 watts over 30 minutes or more, and a first- or second-generation Ryzen has very similar problems.
I measure the two EPS rails in real time with my special measuring setup (picture above) for motherboards and have also stored a comparison curve for plausibility, which takes into account the voltage converter losses at the respective power levels. The displayed sensor values for the package power plus these losses are quite exactly the same as what I am doing in terms of performance. This was a very precise way of finding out the BIOS settings that I also need for an exact limitation to obtain the most constant power dissipation possible.
Unfortunately, it is not enough in the BIOS e.g. just set 125 watts, because that will definitely go wrong. With the Aorus X299 Master I used, there are already 11 watts more, which you have to release via BIOS. Unfortunately, you can't avoid exact calibrations in advance. The fixation of the CPU clock is no longer necessary and you can really concentrate on the actual waste heat, which is essential in a cooler test.
Why a Ryzen 3 doesn't make sense
Even if the AMD Ryzen of the third generation as 12- or 16-corers could also achieve power losses of 200 watts and more, which is quite possible with the Chiller – with room temperatures of 22 °C+ and air as the final cooling medium, this definitely goes wrong, even with Open-loop water cooling. In addition to the special features of the Ryzen CPUs, however, I will soon publish a special article with measurement series, which one would certainly not have suspected in the end result.
I still use a system with the Ryzen 9 3900X for all tests, but limit the TDP to a maximum of 185 watts (see above). Since with these CPUs every cooler always performs similarly from a certain, high cooling performance and the layers up to the radiator floor as the sum of the heat resistances at the resulting high heat flux density form the actual bottleneck, one can with it do not test coolers against each other. But I still accept this extra effort, because I want to know if he manages to cool the 3900X in the given performance window. So it will be more of a yes and no evaluation, which is not worthwhile for real comparisons.
I have also summarized the individual components of the test system in tabular form.
Test System and Equipment |
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Hardware: |
Aorus X299 Master AMD Ryzen 9 3900X 2x 8GB G.Skill SniperX DDR4 3200 |
Cooling: |
Alphacool Polar Bear Aurora Thermal Grizzly Kryonaut |
Case: |
Lian Li T70, Raijintek Paean Open Benchtable |
Monitor: | BenQ PD3220U |
Power Consumption: |
MCU-based: Scope-based: Voltage and Resistance: |
Thermal Imager: |
1x Optris PI640 + 2x Xi400 Thermal Imagers Pix Connect Software Type K Class 1 thermal sensors (up to 4 channels) |
Acoustics: |
NTI Audio M2211 (with calibration file) Steinberg UR12 (with phantom power for the microphones) Creative X7, Smaart v.7 Own anechoic chamber, 3.5 x 1.8 x 2.2 m (LxTxH) Axial measurements, perpendicular to the center of the sound source(s), measuring distance 50 cm Noise emission in dBA (slow) as RTA measurement Frequency spectrum as graphic |
Os: | Windows 10 Pro (1909, all Updates) |
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