iXBT Labs - Computer Hardware in Detail






Scythe Ninja Plus Rev.B, Infinity,
and Andy Samurai Master Coolers


  1. Technical properties
  2. Test results, stock configurations
  3. Test results, configurations with Scythe S-Flex and Minebea fans,
    dual-fan assemblies. Bottom line

Test results, stock configurations

In order to examine thermal efficiency of the coolers, we used our standard Socket 478 cooler procedure along with the current testing procedures for AMD Socket 754/939/AM2 platforms. The primary source of the data is the thermal diode built into the processor. Our test system is based on an Intel Pentium 4 550 and an ASUS P5AD2-E Premium motherboard.

We are also measuring the temperatures of the inductance coils in the CPU voltage regulator. To be specific, we are measuring the temperatures of the PL24, PL25 and PL26 inductance coils near the socket. This provides additional data that helps us evaluate the cooling efficency. CPU voltage is also raised to 1.525 V in order to generate more heat in the testbed. The resulting heat power is 150 W.

Testbed configuration:

  • Motherboard: ASUS P5AD2-E Premium rev. 1.05
  • Processor: Intel Pentium 4 550 (3.4 GHz Prescott, HT Technology)
  • OS: Microsoft Windows XP

We use the S&M utility to create maximum thermal load on the processor and Speedfan monitors temperatures. The Thermal Monitor is disabled in all tests.

Let's proceed to the test results!

Stock configurations

Diagram 1. Temperature readings (CPU core temperature)

Each cooler is tested with Stars 420 thermal paste
The diagram contains complex results.
Diagram 2. Thermal resistance

Thermal resistance θja is defined as the relation
θja = (Tj - Ta)/Ph, where Tj is the temperature of a CPU core, Ta is the environment temperature (it's 25°C in this case), Ph is the thermal capacity of a processor (in this case it's 150 W).
Diagram 3. Temperature readings (temperature of near-socket components)

At the end of this article we publish the noise measurement results (the procedure is described in the article Noise characteristics of coolers and the noise measurement method) as well as the efficiency/noise rating of the coolers.

Diagram 4. Noise characteristics

Note: Background noise level 18 dBA.
Diagram 5. Efficiency/noise ratio

The efficiency/noise ratio (ENR) is calculated as:

ENR = DM*(Rt/TC)/(NL/Rn), where

Rt - reference temperature (the reference thermal resistance θja of the cooling system - 0.25°C/W), TC - the core temperature with the operating cooling system, Rn - reference noise (the reference noise level is 20 dBA), NL - noise level, generated by the cooling system, DM - denominate multiplier (10).


  1. Technical properties
  2. Test results, stock configurations
  3. Test results, configurations with Scythe S-Flex and Minebea fans,
    dual-fan assemblies. Bottom line
Vitali Crinitsin (vit@ixbt.com)
August 4, 2007

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