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Cathar · 05-20-2004, 11:29 PM

Water blocks, for a while there, were extremely low restriction.

We really only need around 0.75gpm (~3LPM) flow rates to do decent water cooling in the sense that the thermal resistance due to the volume of the water is not a significant factor in the level of cooling for which the water block can offer. The C/W of 0.75GPM of water is almost bang on 0.005, or low enough to be insignificant. Doubling the flow rate to 6LPM only yields a 0.0025 C/W improvement for the water mass, or about 0.25C for a 100W CPU.

So if we set our sights on 3LPM as being a minimum desirable flow rate, then this means that 3/8" ID tubing can make quite a lot of sense. 1 meters of 3/8" ID tubing at 3LPM provides around 9cm of pressure drop.

I'd like to make a block that peaks out at around 4LPM with an MCP600 attached to it. Only problem is with the public perception. It seems that the public needs to be eased into such an understanding. One of the prototypes I designed (on paper) did just that - as in it was restrictive enough that it would cause an Eheim 1250 to only run at slightly above 0.75GPM. Problem is that people would freak out at a block that had ~4PSI of pressure drop at 1GPM. I can imagine JoeC's comments at OC.com even now - "Absurdly high pressure drop block requiring a monster pump!" - when really all the block needs is just your every day pump that everyone uses to achieve the cooling purpose for which it was designed.

I find JoeC's comments somewhat contradictory. He comments on the need for powerful pumps for blocks that will happily run at the 1GPM that he tests at when driven with even quite weak pumps.

I believe that there is a place for 3/8" ID tubing - it's just that the market needs to be eased back into that understanding. There is an obsession with monster flow rates, because the very low pressure drop blocks often required those flow rates to perform well. The high flow rates (>5LPM) necessitated the need for 1/2" ID tubing, and it's not that 1/2" ID tubing is needed to push the flow rates that are required for adequate cooling at a fundamental level.

[Edit: fixed units in one location]

05-20-2004, 11:29 PM	#15
Cathar Thermophile Join Date: Sep 2002 Location: Melbourne, Australia Posts: 2,538	Water blocks, for a while there, were extremely low restriction. We really only need around 0.75gpm (~3LPM) flow rates to do decent water cooling in the sense that the thermal resistance due to the volume of the water is not a significant factor in the level of cooling for which the water block can offer. The C/W of 0.75GPM of water is almost bang on 0.005, or low enough to be insignificant. Doubling the flow rate to 6LPM only yields a 0.0025 C/W improvement for the water mass, or about 0.25C for a 100W CPU. So if we set our sights on 3LPM as being a minimum desirable flow rate, then this means that 3/8" ID tubing can make quite a lot of sense. 1 meters of 3/8" ID tubing at 3LPM provides around 9cm of pressure drop. I'd like to make a block that peaks out at around 4LPM with an MCP600 attached to it. Only problem is with the public perception. It seems that the public needs to be eased into such an understanding. One of the prototypes I designed (on paper) did just that - as in it was restrictive enough that it would cause an Eheim 1250 to only run at slightly above 0.75GPM. Problem is that people would freak out at a block that had ~4PSI of pressure drop at 1GPM. I can imagine JoeC's comments at OC.com even now - "Absurdly high pressure drop block requiring a monster pump!" - when really all the block needs is just your every day pump that everyone uses to achieve the cooling purpose for which it was designed. I find JoeC's comments somewhat contradictory. He comments on the need for powerful pumps for blocks that will happily run at the 1GPM that he tests at when driven with even quite weak pumps. I believe that there is a place for 3/8" ID tubing - it's just that the market needs to be eased back into that understanding. There is an obsession with monster flow rates, because the very low pressure drop blocks often required those flow rates to perform well. The high flow rates (>5LPM) necessitated the need for 1/2" ID tubing, and it's not that 1/2" ID tubing is needed to push the flow rates that are required for adequate cooling at a fundamental level. [Edit: fixed units in one location] Last edited by Cathar; 05-22-2004 at 08:27 AM.