Pro/Forums - View Single Post - Thoughts on water pressure & flow rate...

8-Ball · 04-18-2003, 08:10 PM

Oh go on then, one more try.

In the thread re your tiny waterblock, you stated that you need a temperature gradient to move the heat (I almost thought you actually DID know what you were talking about when I saw that and that you'd been stringing us all along. Not to be I guess)

It's still the same.

The temperature difference sets up a temp gradient which will provide a driving force for the transfer of heat from the cpu to the waterblock.

If for some reason the coolant rose in temp (like you'd suddenly plugged a hot tap/fawcet into your loop), the temp difference would be too low. Ie the temp gradient would be shallower. I believe from your other thread that you understand the implications of this. Less than the "70W" will be tranferred from the cpu to the waterblock. But the processor is still producing "70W", so, excess thermal energy will begin to build up in the processor.

This will cause the temperature in the processor to rise. As this happens, the temp gradient will gradually steepen, driving more and more heat off the processor per second as it steepens, until a point comes when the gradient is the same as it was before, allowing the transfer of 70W of heat from the processor to the block. The processor will stabilise at this temperature, because it is producing 70W and the temp gradient is just right to transfer 70W. You could say it is in equilibrium.

Now suppose the cpu begins to idle. The power output drops to 60W, yet there is still a gradient driving 70W of heat into the block. Because the block is now removing more heat than is being produced, the cpu will cool down, with the thermal gradient getting shallower as it does so, until such a point is reached where 60W is transferred to the waterblock. Again, the temp will stabilise, and the cpu and the block are "at equilibrium".

In reality, this process happens very quickly, with the heat removed by the block matching the fluctuations of the cpu power output.

I hope this makes sense, as it is a key principle to understand.

If not, query it bt by bit and myself or others will try and help. We may come across as stubborn, but we would be less so if you stopped and listened to what we said just for a moment, to allow a coherent argument to be put together.

What do you think?

8-ball

PS, sorry if I came across as a little harsh earlier.

04-18-2003, 08:10 PM	#84
8-Ball Cooling Savant Join Date: Feb 2002 Location: Oxford University, UK Posts: 452	Oh go on then, one more try. In the thread re your tiny waterblock, you stated that you need a temperature gradient to move the heat (I almost thought you actually DID know what you were talking about when I saw that and that you'd been stringing us all along. Not to be I guess) It's still the same. The temperature difference sets up a temp gradient which will provide a driving force for the transfer of heat from the cpu to the waterblock. If for some reason the coolant rose in temp (like you'd suddenly plugged a hot tap/fawcet into your loop), the temp difference would be too low. Ie the temp gradient would be shallower. I believe from your other thread that you understand the implications of this. Less than the "70W" will be tranferred from the cpu to the waterblock. But the processor is still producing "70W", so, excess thermal energy will begin to build up in the processor. This will cause the temperature in the processor to rise. As this happens, the temp gradient will gradually steepen, driving more and more heat off the processor per second as it steepens, until a point comes when the gradient is the same as it was before, allowing the transfer of 70W of heat from the processor to the block. The processor will stabilise at this temperature, because it is producing 70W and the temp gradient is just right to transfer 70W. You could say it is in equilibrium. Now suppose the cpu begins to idle. The power output drops to 60W, yet there is still a gradient driving 70W of heat into the block. Because the block is now removing more heat than is being produced, the cpu will cool down, with the thermal gradient getting shallower as it does so, until such a point is reached where 60W is transferred to the waterblock. Again, the temp will stabilise, and the cpu and the block are "at equilibrium". In reality, this process happens very quickly, with the heat removed by the block matching the fluctuations of the cpu power output. I hope this makes sense, as it is a key principle to understand. If not, query it bt by bit and myself or others will try and help. We may come across as stubborn, but we would be less so if you stopped and listened to what we said just for a moment, to allow a coherent argument to be put together. What do you think? 8-ball PS, sorry if I came across as a little harsh earlier. __________________ For those who believe that water needs to travel slowly through the radiator for optimum performance, read the following thread. READ ALL OF THIS!!!!