Scythe NCU-2000 Fanless CPU Cooler

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TEST RESULTS

No fans were anywhere near the CPU heatsink or motherboard. The ambient temperature was 23°C. The NCU-2000 made no noise whatsoever.

NCU-2000 Fanless Performance
Idle
General Apps
Folding
Max Temp
Max Temp Rise
°C/W
TDP
°C/W
MP
55
57~62
64
72
49
0.71
0.62
* All figures except °C/W in in °C.
TDP (Thermal Design Power of CPU) = 69W
MP (Maximum Power of CPU) = 79W
Ambient temperature = 23°C

All the temperatures are pretty bad by fan-cooled HS standards, where we often record performance that's twice as good. However, it is important to keep in mind that the HS did not get any help from any fans anywhere near the system. In a real PC, you will almost invariably have a PSU with a fan or a back panel exhaust fan. Even spinning very slowly with low noise, a single fan will cause enough airflow through the open fins of the NCU-2000 to lower the CPU temperature.

The system did not crash at any time. Running folding@home is a pretty good approximation of the typical highest load most desktop users are likely to reach. We have never been able to achieve the load of CPUBurn with any combination of actual applications. Running stress programs like CPUBurn is explicitly cautioned against in the NCU-2000 instructions, you will recall.

The 64°C seen with folding@home is around the high borderline of safe P4 temps. This was with an ambient of 23°C, so add another 10-12°C to estimate in-case temperature, and we have 74-76°C, at which point thermal throttling will probably occur with most P4s. However, airflow created by case fans will certainly impact this temperature as well.

NCU-2000 VS. NCU-1000

How does the performance of the NCU-2000 compare with the NCU-1000?

The NCU-1000 was tested last year on a different platform, the most important differences being:

  • Intel P4-2.53 processor. TDP is 61.5W; Max Power is 72W. 71° C rated maximum junction temp.
  • Gigabyte GA-81RXP motherboard - Intel 845 chipset; on-die thermal diode monitoring.

Keep in mind that the temperate readout was not calibrated and temperature readings are not directly comparable to the results with the current test platform. In the NCU-1000 review, I wrote, "thermal overload... using CPUBurn occurred in little over 10 minutes; the program crashed. As cautioned by the manufacturer, the NCU-1000 is not designed for this kind of stress." In contrast, neither the CPUBurn program nor the system ever crashed during testing, and this is with a CPU that runs 7-8W hotter.


NCU-1000 on current test rig.

For confirmation, I pulled the NCU-1000 sample out of mothballs and installed it on the current P4-2.8 test platform. I let idle overnight then had a look at the temperatures the next morning. The results were surprisingly poor; enough so that I decided to reinstall the HS altogether and run further tests on the following day. The second set of tests were within 1°C of the first set. The NCU-1000 results are compared with those for the NCU-2000 in the table below.

NCU-2000 Vs. NCU-1000, fanless
HS
Idle
Folding
Max Temp
Max Temp Rise
°C/W
TDP
°C/W
MP
NCU-2000
55
64
72
49
0.71
0.62
NCU-1000
63
72
-
-
-
-
* All figures except °C/W in in °C.
TDP (Thermal Design Power of CPU) = 69W
MP (Maximum Power of CPU) = 79W
Ambient temperature = 23°C

There was no point running CPUBurn on the NCU-1000; it would have crashed and/or the CPU retreat into thermal throttling. I wrote in the NCU-1000 review, "I am not in complete agreement about the "up to P4-2.8" (>68W) recommendation for this cooler" when used as intended, without a direct cooling fan. My original opinion is confirmed. It's also clear that the NCU-2000 is a significantly improved performer.

Interestingly, in all the verbiage supplied with the package, there is no mention of the highest speed CPU recommended for use with the NCU-2000. This is probably wise from a legal point of view, and perhaps also from a marketing point of view. The buyer who needs explicit, plain-as-day instructions may not be an ideal user of the NCU-2000.



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