T-Shirt wrote:if there is some space (enclosed area called a plenum) between the fan and radiator, with enough area for the air pressure/suction to equalize, it shouldn't make a difference. the cooling is -X cfm@ y º over the radiator transfers D BTU. The temprature difference of the air (considered a fluid, for this calculation) entering and leave the radiator is call the Delta.
The factors that MIGHT change the results in a VERY MINOR way are the heat from the fan motor in a push setup (not really a factor), the size/design of the plenum (important in push or pull, air pressure MUST equalize and air MUST flow evenly across the radiator surfaces) AND (the biggie!) the design of the fan (some blade shapes are better at suction)
Overall I always choose pull to make vacuuming out the inflow side of the radiator easy to do (a few blocked fins or even a thin layer of dust effect heat transfer more than all the other factors combined.
Which in laymans terms, means a user will see a better improvement in temps by using a shroud, regardless of if they choose a push or pull config.

The shrould is what creates the plenum so the air flows equally through all parts of the radiator.
Methious wrote:Just a minor update, I finally got to the hardware store and replaced the stand off screws I use to distance the radiator from the case. The original bolts were a half inch long (all I had with the same threads at the time), the new ones are 1 3/4" and push the radiator well out from the case, idle temps went from 27 to 23/24C

Needless to say 24 cents worth of bolts and now I'm completely happy with the water cooling move!
Nice... as Tshirt and Bio-hazard have both said, that spacing gap is important for both sides of the radiator(s).

I'm due to teardown my own loop soon, I have a gremlin sapping the performance somewhere that I need to find...