Some interesting developments on my front with the micro-channel block.
So I've cut out a small plastic disc and inserted it under the central inlet barb. Out of that disc I've cut a 5mm wide x 15mm long rectangle that straddles the channels, giving a reasonably small entrance for each channel to receive water. This effectively boosts the water velocity and creates impingement jet streams directly over the heat source.
I also picked up a Pondmaster 4200 pump today too, which pushes 1000lph at 4m head, and close to 4000lph in wide-open mode.
Okay, now we get to the interesting bits of comparing nozzled and non-nozzled performance with the Eheim 1250 vs the Pondmaster 4200.
An AthlonXP CPU was set to 1925MHz/2.15v using BurnK7 to generate full load.
The following CPU die temperatures were observed above the water temperatures (reading the on-die diode of the CPU).
Eheim 1250 - No nozzle - 8.0lpm: +18.5C
Eheim 1250 - Nozzled - 7.0lpm: +18.0C (really it's more like +18.25C - temps kept flipping)
Pondmaster - No nozzle - ~15lpm: +18.0C
Pondmaster - Nozzled - 12.0lpm: +17.0C
What's interesting here is that the nozzled block improves in performance as the flow rates are picked up more than the un-nozzled block.
The Eheim 1250 seems to be struggling to get enough flow to make the jet impingement principle work properly, but the pondmaster's extra pressure ensures that the water velocity through the nozzle is boosted enough to get real benefits of jet impingement.
What's uncertain here is where there's more to be gained in terms of the nozzled vs non-nozzled configuration as the flow rates are picked up even more, or if the full benefits of the jet impingement is being realised already.
I believe this is on the right track, by mixing the two proven cooling methodologies of micro-channels and jet impingement, coupled with a pump capable of the water pressure and flow rates to make it all come together as a functioning whole.
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