Further reflections on watercooling: Difference between revisions

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The non-linearity of the r² term is obvious here: the Quantum Torque inner diameter is 80.3% of the EK-AH's, but the total volume is only 64.4%. Either way, 10mm of the tubing is 1.267mL, so you're talking ¾ or ½ of that in the fitting. Assuming half-inch tubing, you can thus subtract 0.666mL for every Quantum Torque compression fitting, or 0.334 for every EK-AH. A 200mL reservoir would represent almost 600 times this latter value. You can use this same reasoning to calculate the (very small) volume loss at each fitting juncture—just use the inner diameter of the threading.

* When completely idled, a modern processor ought be using only a handful of watts. This is insubstantial heating at the surface area of an integrated heat spreader / waterblock. Ergo, an idled processor ought report temperatures ~~roughly equal to~~ the coolant's temperature. If an idle processor reports temperatures more than ~~a degree~~ or ~~two~~ over the coolant's temperature (modulo any systematic error in your sensors), you have most likely fucked up application of the thermal paste. If they don't, you most likely haven't; congratulations.

* When completely idled, a modern processor ought be using only a handful of watts. This is insubstantial heating at the surface area of an integrated heat spreader / waterblock. Ergo, an idled processor ought report temperatures not much greater than the coolant's temperature; this certainly ought be a constant. If an idle processor reports temperatures more than ten degrees or so over the coolant's temperature (modulo any systematic error in your sensors), you have most likely fucked up application of the thermal paste. If they don't, you most likely haven't; congratulations.

* Sensors are notoriously inaccurate. You can explore their relative systematic inaccuracy by placing them immediately after one another in series (this can of course be changed later). Sensors like to be level relative to gravity.

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* It is natural that pockets of air will persist in your system after filling it. Microbubbles will eventually diffuse naturally out of the system, but larger bubbles need your help. Air, being lighter than water, naturally moves to the local top of a section of the loop. It is thus advisable that your reservoir (and filling point) be as high in the loop as possible. Rotate the machine while the pump is running, attempting to coax the bubble to your reservoir (or any point where you can allow air to leave). Eventually, the air will leave (often with an audible burp), and your coolant level will fall. Top off the coolant (this is why you wanted the air to leave via your refill point), and live happy.

If you calculated your total volume accurately, and track how much fluid you've added, you can know to your satisfaction when you've eliminated all air. This can be useful when you have opaque volumes (like most radiators—I've never seen a transparent radiator, don't know why, it would be cool) at the top of your loop. With that said, it's pretty difficult to get your total volume calculation accurate to more than a few mL, which can be a significant amount of air if it's in e.g. a waterblock.

If you calculated your total volume accurately, and track how much fluid you've added, you can know to your satisfaction when you've eliminated all air. This can be useful when you have opaque volumes (like most radiators—I've never seen a transparent radiator, don't know why, it would be cool. I guess you can't get highly thermally conductive clear materials?) at the top of your loop. With that said, it's pretty difficult to get your total volume calculation accurate to more than a few mL, which can be a significant amount of air if it's in e.g. a waterblock.

* [https://en.wikipedia.org/wiki/Pascal%27s_law Pascal's principle] states that a pressure change at any point in a confined incompressible fluid is transmitted through the fluid such that the change acts everywhere. This has various effects:

** Opening a horizontal port lower than other fluid in the loop will see fluid leave that port until the heights are equalized, once again making a big mess.

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* Adding more power increases flow rates more as the total power level increases. I.e. going to 50% from 25% PWM adds less flow than going from 75% to 100%. This is contrary to my intuition.

And one final, probably controversial point, from my own experiments: '''~~modern~~ waterblocks are very effective even at low flow rates'''. According to my two sensors, I have never managed to exceed 1L/min in my loop, even when using two D5 pumps. My loop is quite large, and climbs over a meter through the height of my very large case, but this still seems a lower flow rate than one might expect from two D5 pumps (admittedly at low power settings). Common hearsay is that one wants at least 0.5G/min (1.9L/min); I rarely manage even half of this. Regardless, my temperatures are excellent, both when measured absolutely at the heat generating sources and when the coolant is measured relative to ambient. Optimizing for flow seems a foolish errand, and ought be of only secondary concern when designing a loop.

And one final, probably controversial point, from my own experiments: '''quality waterblocks are very effective even at low flow rates'''. According to my two sensors, I have never managed to exceed 1L/min in my loop, even when using two D5 pumps. My loop is quite large, and climbs over a meter through the height of my very large case, but this still seems a lower flow rate than one might expect from two D5 pumps (admittedly at low power settings). Common hearsay is that one wants at least 0.5G/min (1.9L/min); I rarely manage even half of this. Regardless, my temperatures are excellent, both when measured absolutely at the heat generating sources and when the coolant is measured relative to ambient. Optimizing for flow seems a foolish errand, and ought be of only secondary concern when designing a loop.

'''previously: "[[Reflections_on_watercooling|reflections on watercooling]]" 2022-04-17'''

[[Category:Blog]]

@@ Line 61: / Line 61: @@
 The non-linearity of the r² term is obvious here: the Quantum Torque inner diameter is 80.3% of the EK-AH's, but the total volume is only 64.4%. Either way, 10mm of the tubing is 1.267mL, so you're talking ¾ or ½ of that in the fitting. Assuming half-inch tubing, you can thus subtract 0.666mL for every Quantum Torque compression fitting, or 0.334 for every EK-AH. A 200mL reservoir would represent almost 600 times this latter value. You can use this same reasoning to calculate the (very small) volume loss at each fitting juncture—just use the inner diameter of the threading.
-* When completely idled, a modern processor ought be using only a handful of watts. This is insubstantial heating at the surface area of an integrated heat spreader / waterblock. Ergo, an idled processor ought report temperatures roughly equal to the coolant's temperature. If an idle processor reports temperatures more than a degree or two over the coolant's temperature (modulo any systematic error in your sensors), you have most likely fucked up application of the thermal paste. If they don't, you most likely haven't; congratulations.
+* When completely idled, a modern processor ought be using only a handful of watts. This is insubstantial heating at the surface area of an integrated heat spreader / waterblock. Ergo, an idled processor ought report temperatures not much greater than the coolant's temperature; this certainly ought be a constant. If an idle processor reports temperatures more than ten degrees or so over the coolant's temperature (modulo any systematic error in your sensors), you have most likely fucked up application of the thermal paste. If they don't, you most likely haven't; congratulations.
 * Sensors are notoriously inaccurate. You can explore their relative systematic inaccuracy by placing them immediately after one another in series (this can of course be changed later). Sensors like to be level relative to gravity.
@@ Line 75: / Line 75: @@
 * It is natural that pockets of air will persist in your system after filling it. Microbubbles will eventually diffuse naturally out of the system, but larger bubbles need your help. Air, being lighter than water, naturally moves to the local top of a section of the loop. It is thus advisable that your reservoir (and filling point) be as high in the loop as possible. Rotate the machine while the pump is running, attempting to coax the bubble to your reservoir (or any point where you can allow air to leave). Eventually, the air will leave (often with an audible burp), and your coolant level will fall. Top off the coolant (this is why you wanted the air to leave via your refill point), and live happy.
-If you calculated your total volume accurately, and track how much fluid you've added, you can know to your satisfaction when you've eliminated all air. This can be useful when you have opaque volumes (like most radiators—I've never seen a transparent radiator, don't know why, it would be cool) at the top of your loop. With that said, it's pretty difficult to get your total volume calculation accurate to more than a few mL, which can be a significant amount of air if it's in e.g. a waterblock.
+If you calculated your total volume accurately, and track how much fluid you've added, you can know to your satisfaction when you've eliminated all air. This can be useful when you have opaque volumes (like most radiators—I've never seen a transparent radiator, don't know why, it would be cool. I guess you can't get highly thermally conductive clear materials?) at the top of your loop. With that said, it's pretty difficult to get your total volume calculation accurate to more than a few mL, which can be a significant amount of air if it's in e.g. a waterblock.
 * [https://en.wikipedia.org/wiki/Pascal%27s_law Pascal's principle] states that a pressure change at any point in a confined incompressible fluid is transmitted through the fluid such that the change acts everywhere. This has various effects:
 ** Opening a horizontal port lower than other fluid in the loop will see fluid leave that port until the heights are equalized, once again making a big mess.
@@ Line 117: / Line 117: @@
 * Adding more power increases flow rates more as the total power level increases. I.e. going to 50% from 25% PWM adds less flow than going from 75% to 100%. This is contrary to my intuition.
-And one final, probably controversial point, from my own experiments: '''modern waterblocks are very effective even at low flow rates'''. According to my two sensors, I have never managed to exceed 1L/min in my loop, even when using two D5 pumps. My loop is quite large, and climbs over a meter through the height of my very large case, but this still seems a lower flow rate than one might expect from two D5 pumps (admittedly at low power settings). Common hearsay is that one wants at least 0.5G/min (1.9L/min); I rarely manage even half of this. Regardless, my temperatures are excellent, both when measured absolutely at the heat generating sources and when the coolant is measured relative to ambient. Optimizing for flow seems a foolish errand, and ought be of only secondary concern when designing a loop.
+And one final, probably controversial point, from my own experiments: '''quality waterblocks are very effective even at low flow rates'''. According to my two sensors, I have never managed to exceed 1L/min in my loop, even when using two D5 pumps. My loop is quite large, and climbs over a meter through the height of my very large case, but this still seems a lower flow rate than one might expect from two D5 pumps (admittedly at low power settings). Common hearsay is that one wants at least 0.5G/min (1.9L/min); I rarely manage even half of this. Regardless, my temperatures are excellent, both when measured absolutely at the heat generating sources and when the coolant is measured relative to ambient. Optimizing for flow seems a foolish errand, and ought be of only secondary concern when designing a loop.
 '''previously: "[[Reflections_on_watercooling|reflections on watercooling]]" 2022-04-17'''
 [[Category:Blog]]

Further reflections on watercooling: Difference between revisions

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