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10-25-2001, 07:07 AM

I think flow rate is important but not as much as many believe. Thermal transfer works better with a large difference... IE heat will transfer from a hot plate to an ice cube more quickly than an ice cube to a table top. So you want the water in the cooler to have a larger temperature difference compared to the waterblock. If the flow rate is too low then as the water passes through the cooler it will heat up and .5-.75 of the way through it will have almost matched the waterblock temp, thus no more heat is being transferred. As long as there is enough flow that it keeps a good differential all the way through, it will be fine. More flow will help in that the differential will be higher for more of the trip thru the block. This holds true for the radiator too-- if the water has cooled down to the rad temp halfway through, that extra distance is not being utilized. This is why good flow helps.

However this curves off... the gain from 100gph to 250gph will be more than the gain from 250 to 500. As long as a good differential is being maintained all the way through, more flow will only help marginally (will only increase the temp difference a little bit). This is not to say more flow doesnt help... it does. Just not as much.

Also anyone who tells you too much flow is bad for heat transfer is probably wrong. The only way too much flow would be bad is if you blow a gasket from too much pressure. The argument 'it doesnt stay in the radiator long enough' is bullshit. Dont forget that higher flow means it stays in the water block for less time too, so its cooler as it comes out. It being cooler in the radiator means the same differential effect applies. But what you lost with a lower radiator differential you gain in a higher water block differential. So more heat is being sucked off the core and thus it works marginally better.

Bottom line...
Dont waste your money on a 1000gph pump if all you got is one CPUblock and one radiator, you're wasting your money and raising the pressure (more chance of leaky fittings). Go for a 250 or at most a 500. If you have several blocks, IE CPU, graphics, HDD, etc. that same 250-500 will probably do just fine, if you feel adventurous get a 650. My suggestion-- hook the blocks in parallel. IE get a Y adapter that splits the pump output to go to both CPU and everything else. IE if you have graphics and hard drive, split the 'everything else' one again. Then recombine them before the radiator. Two radiators in parallel and large diameter tubing between the pump and first Y will give you a huge flow boost.

Am I rambling? I think I am. I wonder where the word rambling came from? Now lets see...

10-25-2001, 07:07 AM	#6
IronHelix Guest Posts: n/a	I think flow rate is important but not as much as many believe. Thermal transfer works better with a large difference... IE heat will transfer from a hot plate to an ice cube more quickly than an ice cube to a table top. So you want the water in the cooler to have a larger temperature difference compared to the waterblock. If the flow rate is too low then as the water passes through the cooler it will heat up and .5-.75 of the way through it will have almost matched the waterblock temp, thus no more heat is being transferred. As long as there is enough flow that it keeps a good differential all the way through, it will be fine. More flow will help in that the differential will be higher for more of the trip thru the block. This holds true for the radiator too-- if the water has cooled down to the rad temp halfway through, that extra distance is not being utilized. This is why good flow helps. However this curves off... the gain from 100gph to 250gph will be more than the gain from 250 to 500. As long as a good differential is being maintained all the way through, more flow will only help marginally (will only increase the temp difference a little bit). This is not to say more flow doesnt help... it does. Just not as much. Also anyone who tells you too much flow is bad for heat transfer is probably wrong. The only way too much flow would be bad is if you blow a gasket from too much pressure. The argument 'it doesnt stay in the radiator long enough' is bullshit. Dont forget that higher flow means it stays in the water block for less time too, so its cooler as it comes out. It being cooler in the radiator means the same differential effect applies. But what you lost with a lower radiator differential you gain in a higher water block differential. So more heat is being sucked off the core and thus it works marginally better. Bottom line... Dont waste your money on a 1000gph pump if all you got is one CPUblock and one radiator, you're wasting your money and raising the pressure (more chance of leaky fittings). Go for a 250 or at most a 500. If you have several blocks, IE CPU, graphics, HDD, etc. that same 250-500 will probably do just fine, if you feel adventurous get a 650. My suggestion-- hook the blocks in parallel. IE get a Y adapter that splits the pump output to go to both CPU and everything else. IE if you have graphics and hard drive, split the 'everything else' one again. Then recombine them before the radiator. Two radiators in parallel and large diameter tubing between the pump and first Y will give you a huge flow boost. Am I rambling? I think I am. I wonder where the word rambling came from? Now lets see...