Yes and no Brad. BillA has better resolution of temps, but he sees basically the same thing:
"The trend lately in pump selection seems to be towards over-sizing, with the rationale that the output can then be throttled back to find "the sweet spot" where the maximum cooling (minimum temperature) is obtained. It has been shown that some (few) radiators do indeed seem to have a point of higher performance, but this is not so for most.
To understand the watercooling system "sweet spot" concept, another bit of information is needed - the relationship between the coolant's flow and heat transfer in the waterblock. The graph below illustrates this for a popular waterblock, where the difference is shown between the waterblock baseplate and coolant (inlet) temperatures vs. the flow rate.
The temperature was recorded with a type T thermocouple embedded in the baseplate over the die area (per AMD's recommendations) with a 77 Watt heat load applied through a 100 mm² heat die. For this test, the inlet temperature was held constant, so the reduced temperature difference is in fact the reduction in baseplate temperature attributable to the higher coolant flow rate.
The very significant benefit from higher waterblock flow rates is clear, but this is directly the opposite of the optimum for radiators.
The "sweet spot" determined by throttling the pump output is simply the balancing of the compromised performance of both the waterblock and radiator. This point will be different for each combination of components, and will not exist at all for systems where the waterblock performance gain exceeds the radiator impairment; for such systems more coolant flow is always better, much more. "
(from
http://www.overclockers.com/articles481/index06.asp )
So yes in the absence of a radiator's need to dissipate heat more flow is always better for a block. Even still, if concepts of price/performance (or space/performance) are considered then it is still much more effective to only try to get in the region of optimal performance (1-1.5 gpm for both BillA and my own block testing) and not end up with 1" tubing and fittings and a 1000 GPH pump to try and get that extra little bit of performance.
Why? More cooling is always better, right? Well, it isn't possible to completely isolate the waterblock from the heat dissipation vs flow rate curves of the radiator in the real world, hence this whole concept of sweet spots discussed by BillA at length and myself much more modestly above.
Ok I just woke up from a nap...coffee and then more of this in a bit.