That's a bit the situation here.
If you have access to 2 pumps, and are wiling to use them, serial setup will sure boost your performence.
The 2 rad's should be more than capable to remove the heat.
Also, your CPU will give about 100W of heat, the Northbridge and GPU about 50W
Math is easy... combined through the rad's will give you a temperature drop on the CPU, and a raise on the GPU/NB, compared to a dual loop system (in theory that is)
If your rad's are big enough, then there is no gain.
You can not go colder than ambient temp. If the water temp is more than +/- 8 degrees above ambient, use the two rad'sin one loop. If it is lower, you can try if one rad can handle the (CPU) load.
A raise of 3 degrees in water temp, should give you about 1 degree cpu temp raise. (depending on your setup)
|