Quote:
Originally posted by Kevin
jaydee is partially correct...
While water may change speed inside a block or radiator due to friction, restriction, and channel width, the velocity/flow rate of the water (which are the exact same things btw...), is the same going into the barb as it is coming out.
And for the whole velocity is different than flow rate argument, velocity is a measure of an amount vs. time. Flow rate is gallons (amount) per hour (time).
-Kevin
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Water does not change speed inside a waterblock. What changes is
pressure.
Velocity and flow rate are
not the same thing. Velocity is distance per unit time, whereas flow rate is volume per unit time. Actually, to be more accurate we should say speed, since velocity is distance per unit time + a direction (velocity is a vector), but direction is not important here.
Flow rate is constant throughout the system. It could not possibly be any other way. Could you put more water into something than comes out the other end?
Try this analogy: Imagine a road with one lane, and one mile long. To get a 'flow rate' of one car per minute, each car must travel at 60mph (to take one minute to traverse one mile). Now image a road with six lanes, and one mile long. To get one car per minute dow nthis road, each car need only travel at 10mph, since six cars can fit in parallel.
This is equivalent to how different sized tubes, waterblocks etc can have different water velocities but the same flow rate - the larger the passage, the lower the velocity for a given flow rate. jaydee116 said the same thing in a different way.
Back to the original question: Water is virtually incompressible, so the density won't increase with pressure (increasing heat capacity), and copper is impermeable, so water won't be forced into the surface (which would change cooling). I cannot see any other way that higher water pressure could affect a waterblock's efficiency.
I have tested a water cooling setup with different orders, but I could not detect any significant difference. This was a long time ago though, and without good measurements.