Koolance CPU-345 and CPU-350

Thermal Test Results

Now finally some results! First up, the individual configurations testing.

Wow! Talk about a lack of differentation between orientations (three were tested: with the barbs horizontally, vertically, and at a 45 degree angle). Also interesting was that the new midplate ("New MP") performed identically to the old one. In my previous tests, I noted a .25-.5C difference between the two, but I did something different this time: I marked the outside of the block with Sharpie so that I would reassemble the block identically–last time I assembled by feel. The flowrate of the old midplate configuration was 1.24GPM, easily the most restrictive stock configuration I’ve tested so far. The flowrate with the new midplate went up to 1.40GPM while noticing no degradation in thermal performance. Still shocking just how little this block cares about orientation–something rare from a high performance block these days.The CPU-345 is quietly sitting back behind the CPU-350, but the difference was surprisingly small, only a ~1.7C drop in performance. The CPU-345 is very low restriction (about the same as the Heatkiller 3.0 LC) and has the same solid mounting mechanism that the CPU-350 uses. This block is a sleeper.

Specific Pumping Power

Now that we’ve figured out what the best configuration is for each block, let’s chart its performance over the entire flowrate spectrum.

  • Very High Pumping Power: All three MCP355 pumps and the D5 are on at full speed–this has a very similar PQ curve to a pair of RD-30s at 20V.
  • High Pumping Power: Two MCP355s with EK V2 tops are on at full speed. The other two pumps are off.
  • Medium High Pumping Power: A single MCP355 with XSPC V3 top is on at full speed. The other three pumps are off.
  • Medium Pumping Power: The stock D5 is on at full speed and setting 5. The other three pumps are off.
  • Low Pumping Power: A single MCP355 with XSPC V3 top is on at minimum speed (~7.7V, ~2450RPM). The other three pumps are off.
  • Very Low Pumping Power: The stock D5 is on at minimum speed–setting 1. The other three pumps are off.

Note: I do 5 mounts at “Medium High” then take the best config of a block and test the whole flow spectrum (after a TIM curing session) then realign that curve with average of the 3 median mounts to give you the “Adjusted” data.

Other Graphs

More graphs for your enjoyment…let’s start with reusing the flow vs. temperature data, but including pump heatdump (i.e., CPU vs. air temps). I have two iterations of it: CPU temperatures vs. my air temperatures and a setup with my water-to-air delta included twice more. The latter is to mimic a setup with one third the radiator power of my setup (roughly a 120×3 radiator with 1600RPM fans).

Note: these results are derived from adding the water-to-air delta three times to my water temps. I add them three times to emulate the radiator power of a loop with 1/3rd the radiator power mine has. I use 2xMCR320s with push-pull 2200RPM Yate Loons and the data emulates the conditions of a loop with a single 120×3 radiator with ~1600RPM fans.

Here we can see something that, at face value, is somewhat of an odd tendency: the more restrictive block is actually less responsive to increases in pumping power. I don’t have a conclusive explanation why this is, but considering the vast differences in the design of the base, it doesn’t really faze me. Both blocks scale pretty well up until the dual DDCs, with the CPU-350 being more resilient to low flowrates.

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