Why Is Pump->Rad->Block Better?

[richone]

Before I strip down my watercooling rig to try to tweak out a few more degrees, I need to understand why
Pump->Rad->Block->Pump
is better.

I have a submerged pump in a resevoir that currently is setup Pump->Block->Rad->Pump. The system is 47C Cpu(idle, 51C load), 30C Radiator, 27C Ambient. The block is clamped down super tight and AS2 was used. Would changing to Pump->Rad->Block help?

Thx

[derraa]

The submerged pump generates heat. If you have the pump before the radiator, that heat gets dispersed into the air without efecting your processor temp.

[futRtrubL]

If you want increased performance then accepted practice is using an inline pump before the rad. This way the pump adds less heat to the water and the gets rid of it before it reaches the CPU. I have my reservations about this as the heat output of the pump is negligible compared to the CPU exept when idle, when it doesn't matter.
If you want decreased chance of failure and increased longevity then the accepted practice is to use a submerged pump after the rad. This way the pump has less chance of overheating itself and the water is cooler in it. However, pumps that are sold as inline and submerged are sold that way because they are reliable in those positions, and water temp shouldn't get too high anyway.

To make a long story short it's really down to preferance. ;']

Edward

[Brad]

I doubt it really matters, most of the pumps product so little heat. It is a little bit better, but not by much

[Pinkster]

when i changed from pump (inline eheim 1048) from after the rad to b4 the rad my temps actually increased by 2 or 3 degrees C at the same ambient temp. i think its because in this setup it was physically less conveinient the way my components are setup in the case so my pipes were heading all over the place and i had to use more pipe and a 90 degree bend to put pump b4 rad. i think this slowed down waterflow enough to more than cancel out the benifit of the rad cooling the heat produced by the pump. so i say just do it in whatever order is most convenient for the way your components are setup in the case. my experience was with an inline pump though, might be a little different with a submerged pump.

[WebMasta33]

What radiator and fans do you have on it? From what it sounds like, is that your radiator isn't getting enough heat out of your water. This is what I get, but I'm not sure.:shrug:

[Joe]

There may be a minimal effect, but logic shows that you want the heat exchange point that is cooling the coolant as close to the object you are trying to cool as possible.

I have followed that logic in every system I have built, since why would you want to introduce a heat source BEFORE the cpu?

[jaydee]

Originally posted by Joe
There may be a minimal effect, but logic shows that you want the heat exchange point that is cooling the coolant as close to the object you are trying to cool as possible.

I have followed that logic in every system I have built, since why would you want to introduce a heat source BEFORE the cpu?

What he said. The coolest water in the system is the output of the radiator. Therfor you want the output to go directly to the block for the coolest temps.