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System Name | Hotbox |
---|---|
Processor | AMD Ryzen 7 5800X, 110/95/110, PBO +150Mhz, CO -7,-7,-20(x6), |
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... but nobody is discussing that. Why? Because it isn't relevant. As you say, the function is what it is. Physics is not up for debate here. What is variable, and thus interesting to discuss, is the conditions in play: cold plate designs, radiator designs, flow rates, airflow, thermal deltas, liquid volumes, etc. With all of this in play, thermal transfer between materials is just one of many, many functions in play. And going off this, saying "heat exchange is the same at the radiator, the ihs and the water" is a ridiculous oversimplification. It works in the same way (i.e. as long as you know the materials and their temperatures you can make rough calculations based off variants of the same formula), but it is by no means the same - literally every variable is different, from absolute temperatures to deltas to transfer media to surface areas to flow paths to materials and thicknesses. A CPU block has a huge thermal delta (gradual between hot and cold silicon->IHS->cold plate->water) but very little surface area, and depending on cold plate design and CPU hot spot layout potentially very uneven distribution of flow vs. hotspots. A radiator typically has a much, much lower thermal delta (I've never seen a water loop exceed 20 degrees above ambient, but I've seen many CPUs run 40-50 degrees above water temp), has a much larger surface area, typically has very evenly distributed flow, but also transfers heat into a much less efficient medium - air. And, as you hopefully know, the smaller the thermal delta, the less efficient the thermal transfer. Which is why the scenario you posited above - that with an 80-degree CPU, the water in the loop might be 78.9 degrees - is never going to happen as long as there's a radiator in the loop, any liquid flow, and there is any airflow through the radiator. I did see something like that with the clogged Enermax AIO on my partner's Threadripper system - it thermal throttled down to ~600MHz, but due to no flow the water in the pump block housing and the first couple of inches of tubing got ridiculously hot. But once you have an actually functioning water loop, that is never going to happen. The thermal load required to maintain 80-degree water temperatures in any human-survivable ambient temperature with a radiator in the loop would be immense.Really, like equilibrium? That is what I said. Heat exchange is the same at the radiator, the ihs and the water.
Heat transmittance function is not up to debate.
With this many variables in play, starting from an assumption of perfect and immediate thermal transfer is bad methodology. You need to account for the specifics of the system being measured first, unless you want your data to be so fundamentally flawed as to be utterly useless.