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Diago,
As an aside, I just realized what may have been a contributing factor in our disagreement earlier.
I don't think we were talking about the same Delta T.
In retrospect I think you were calculating the temperature of the coolant before and after the block. Is that correct?
The Delta T I was talking about was the temperature difference between the coolant temperature, and the actual silicon core temperature as measured on die.
This is much too complex of a relationship (IMHO) to accurately calculate in theory, as it depends on too many unknowns. Some things we know (coefficient of heat conductance of copper, for instance) but then there are other aspects as well. How flat is the block? How flat is the top of the heatspreader of the chip? What thermal paste is being used? How thick is it in its final mount? What does the chip assembly look like underneath the heat spreader? what is the exact heat dissipation, etc. etc. etc.
I tend to think of water cooling loops from the perspective of two distinct Delta T's.
Ambient Air <---- DT1 ----> Coolant Temp <---- DT2 ----> Die temp.
DT1 depends on a combination of heat load, flow rate, radiator capacity/efficiency and fan speed.
DT2 depends almost exclusively on heat load, block efficiency and flow rate. Since I know I was running the same silicon at the same settings and voltages, I knew that the heat load was the same as before, and the block was the same as before, thus the only variable here is the flow rate, and I feel fairly confident that I can tell the difference in flow rate up based on this delta T value.
This is also why I am a proponent of high flow rates. If I can minimize DT2, I can allow my coolant temp to be higher, and thus lower my fan speeds making everything quieter. a difference of 1C can mean the difference between deafening fans and relative quiet, especially since DT1 heat transfer is more efficient as the DT increases.
In my ideal water loop, the flow rate is high enough where you hvae a perfect steady state, and cannot measure a difference in coolant temp between any two points in the loop. The coolant is passing through so fast that you hvae a complete steady state.
No we were talking about the same Delta T, but i wasn´t specifically talking about the delta T because its just a relative number. For PC Cooling the absolute number should be more important - thats the CPU/GPU Temp.
If your water has 40°C and your delta T is 5K your CPU has 45°C... if your water has only 30°C and your delta T is 10K your CPU has 40°C. That said it is more important to get your water temp down than the delta T.
It´s just a different view point - i would never use 2 pumps to get such a high flow, first because its expensive and uses more power. Second, and that is a simple truth: If your system won´t run when its 3K hotter your cooling solution is not
sufficent at all and you need to make fundamental changes to it.
To get a steady state you don´t need such a high flow. i have about 1 liter (little less) in my system that means it will be circulating about 60 times per hour.. that is pretty fast already.
btw. my delta T (CPU) is 42K right now (125W Ryzen 2700x) - GPU its 12K both at 100% Water temp is 33°C. Flow 53,7L/h
Running a loop at lower flow rate will never increase the performance. You will have higher differential temperatures cold/warm but the average temperature will increase.
Dieser Beitrag wurde bereits 1 mal editiert, zuletzt von »Bartdude« (1. Mai 2020, 06:00)
Running a loop at lower flow rate will never increase the performance. You will have higher differential temperatures cold/warm but the average temperature will increase.
There has been a lot of testing of various water cooling elements in the past, most done HERE I suggest taking a look, testing showed the best flow was between 1-1.5gpm after which you get diminishing returns so most water cooling enthusiasts try to obtain somewhere in that region. I myself have a duel d5 setup and run at just over 1gpm or 237lph.
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