Intel's HSF for high-end Core 2 Extreme CPUs

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Testing was done according to our unique heatsink testing methodology, and the reference fan was profiled using our standard fan testing methodology. A quick summary of the components, tools, and procedures follows below.

Key Components in Heatsink Test Platform:

  • Intel Pentium D 950 Presler core. TDP of 130W; under our test load, it measures 78W including efficiency losses in the VRMs.
  • ASUS P5LD2-VM motherboard. A basic microATX board with integrated graphics and plenty of room around the CPU socket.
  • Samsung MP0402H 40GB 2.5" notebook drive
  • 1 GB stick of Corsair XMS2 DDR2 memory.
  • FSP Zen 300W fanless power supply.
  • Arctic Silver Lumière: Special fast-curing thermal interface material, designed specifically for test labs.

Test Tools

  • Seasonic Power Angel for measuring AC power at the wall to ensure that the heat output remains consistent.
  • Custom-built, four-channel variable DC power supply, used to regulate the fan speed during the test.
  • Bruel & Kjaer (B&K) model 2203 Sound Level Meter. Used to accurately measure noise down to 20 dBA and below.
  • Various other tools for testing fans, as documented in our standard fan testing methodology.

Software Tools

  • SpeedFan 4.32, used to monitor the on-chip thermal sensor. This sensor is not calibrated, so results are not absolute.
  • CPUBurn P6, used to stress the CPU heavily, generating more heat than most real applications. Two instances are used to ensure that both cores are stressed.
  • Throttlewatch 2.01, used to monitor the throttling feature of the CPU to determine when overheating occurs.

Noise measurements were made with the fan powered from the lab's variable DC power supply while the rest of the system was off to ensure that system noise did not skew the measurements. Keep in mind that the fan in the heatsink is a PWM fan, which typically have a narrower speed range when controlled by direct changes in voltages. It may also exhibit slightly different acoustics under PWM speed attenuation.

Load testing was accomplished using CPUBurn to stress the processor, and the graph function in SpeedFan was used to make sure that the load temperature was stable for at least ten minutes. The stock fan was tested at various voltages to represent a good cross-section of its airflow and noise performance.

The ambient conditions during testing were 18 dBA and 20°C.


The material used for the fan made it difficult to get a proper fan speed reading using a tachometer. After finding the noise level at 12V, 9V, 7V and 5V using a custom DC fan controller and our B&K SLM, we hooked the fan up to our test motherboard and used SpeedFan to manipulate and read the fan speeds.

Intel FCLGA4-S Fan (Low) Measurements
SpeedFan Setting
Fan Speed
Noise Level
2050 RPM
90% (~9/12V)
1930 RPM
80% (~7V)
1820 RPM
1690 RPM
1520 RPM
1380 RPM
40% (~5V)
~1300 RPM*
* Estimated (at 40% and below, the fan speed failed to register)

From noise data alone, we extrapolated that the fan spins at approximately 1300 RPM at 5V, 1800 RPM at 7V, and between 1900 and 2000 RPM at 9/12V. These results were obtained with the fan set to low — we had no desire to try it any faster.

Cooling Results

Intel FCLGA4-S
Fan Voltage
Noise @1m
°C Rise
36 dBA
36 dBA
34 dBA
25 dBA
Load Temp: CPUBurn for ~10 mins.
°C Rise: Temperature rise above ambient (20°C) at load.
°C/W: based on the amount of heat dissipated by the CPU (measured 78W); lower is better.

Fan @ 12V: The fan was very aggressive with a noticeable buzzing. The fan also transferred vibration to the heatsink's fins, creating the sound of rattling metal. With a 22°C rise in CPU temperature, it was fairly inefficient considering it emitted an unbearable 36 dBA.

Fan @ 9V: The fan sounded pretty much identical as it did at 12V. Thermals did not change.

Fan @ 7V: The sound level dipped slightly. The rattling of the fins was still evident, but as fan was spinning slower, the frequency of the clanging lowered, creating a harsher acoustic profile. The CPU temperature increased by only a single degree.

Fan @ 5V: The noise level dropped significantly. The rattle was barely noticeable at a distance of 1m. Within a foot of the heatsink, there was a tiny bit of clanging like a very light breeze blowing through a set of wind chimes. The fan whined as well. While this was a great improvement over higher speeds, it still was far from being quiet. On the bright side, there was only a three degree difference compared to the fan at 9 or 12V.

While we were impressed with how little the CPU temperature changed between 1900 and 1300 RPM, the noise it produced was irksome. At 5V, it was still generating 25 dBA. We did not feel it was appropriate to test it any lower as the fan's starting voltage was fairly high (8.4V).

Loose fins rattle and buzz at high frequency.

The source of the rattling and clanging was found to be the loose fin sections in the upper section of the heatsink. During testing we found that compressing them improved the acoustics significantly. The fan itself was not awful, but the way it interacted with the rest of the heatsink was.

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