Originally Posted by 3xtr3m3
I think there is a sweet spot (speed) where the heat will transferred to the water which is passing thru the block. It's where the block's heat and water's heat get balanced.
Youâ€™re aint kiddin...this stuff is confusing! But many times itâ€™s confusing because some of our most basic presumptions are wrong. Once those get straightened out, other things usually start to clear up.
For example, in your description you start with a block at 55 C and then theorize that it gets cooler as the water gets hotter because heat is going from one to the other. At some point theyâ€™re the same (balance.) This is your first incorrect presumption. There is definitely heat, but the temperature of the block is maintained by the energy output from the CPU. That is because these components donâ€™t operate at temperature levels...they operate at energy output levels.
Just as tubing transfers water, the block acts like tubing for energy. Energy simply flows through the block, like water flows through tubing. And as water has a constant rate of flow determined by the pump, the energy has a constant rate of flow as well, determined by the CPU.
Remember that the definition of heat is the transfer of energy. The source of this energy is the CPU. So if youâ€™re folding and your CPU is using 70 watts of energy then you have a constant 70 watts of energy to move into the water (and get rid of in the radiator.) So thereâ€™s never a balance point such as the one you described...if the temperature of the block is 55 C, then it is always at 55 C. Why? Because the constant flow of energy keeps it hot.
Originally Posted by 3xtr3m3
Another amount of 19C follows and now the block is at 32C and the balanced system should be lower than 28C. So This means faster pump will get us to lower tempratures (can't go lower than 19C tho)
What youâ€™re describing here is Wind Chill. Youâ€™re standing out in the cold and youâ€™re okay with a slight breeze but then a big gust comes along and freezes your butt. The temperature of the air didnâ€™t change, but for some reason the wind made you feel colder. The reason you feel colder is because, sure enough, the wind caused more heat to get sucked out of you.
This phenomenon has caused more confusion than any other, the first being the belief that faster flow cools faster. This is wrong. You donâ€™t feel colder because the air molecules are moving faster across your body. You feel colder because MORE AIR moved across your body during the gust that it did in the breeze. Itâ€™s all about volume...not speed. If, somehow, the same volume of air could be moved across your body at a slower speed, you would feel just as cold.
But letâ€™s give speed its due. Faster flow causes more turbulence, which helps with heat transfer. However, when it comes to modern waterblocks, the flow is already turbulent at low flow rates...and more turbulence than you need isnâ€™t necessarily better. With turbulence, thereâ€™s such a thing as too much of a good thing.
But back to volume and your description. In your description you send in more water at 19 C. This is your second incorrect presumption. When youâ€™re standing out in the cold, thereâ€™s lots and lots of cold air available to zip by you. The air temperature is independent of your body temperature. If the speed of the air changes, its temperature stays the same. But in water-cooling the temperature of the water is very closely related to the energy output of the CPU. If the speed of the water changes, then the temperature of the water changes. So your faster water may not be at 19 C any more. It might be at 19.5 C.
This is why the Wind Chill analogy doesnâ€™t work that well. Air temperature isnâ€™t closely tied to the energy that your body burns. In water-cooling, water temperature IS closely tied to the energy that the CPU burns.
Think about that for a while