Zalman CNPS8000: A Worthy Successor?

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As time goes on, fewer and fewer heatsinks continue to support Socket 478, which is rapidly fading into the history of computing. This is the case with the CNPS8000, which does not fit on our standard 478 socket heatsink testing rig.

Instead, our Socket 775 test bench was used. This is the same system used to test the Freezer 7 Pro. Details of the system are outlined below. So far, only five heatsinks have been tested on this system: The Arctic Cooling Freezer 7 Pro, the Spire Verticool II, the Scythe Ninja, and the Thermalright XP-120, and, most recently, the Arctic Cooling Alpine 7. No other heatsinks we have tested are directly comparable with the results of this review. The Pentium 520 used in this test is cooler than most of Intel's soon-to-be-forgotten Prescott and Presler chips, but it is still 15-20W hotter than the P4-2.8 Northwood used in our socket 478 HS testing platform. On the other hand, it is also hotter than almost about every AMD processor on the market, not to mention Intel's new Core 2 Duo chips, many of which draw much less power than the Intel 520.

On the test bench...

Test Platform

Measurement & Analysis Tools

Noise measurements were made with the fan powered from the lab DC power supply with everything else turned off to ensure minimal ambient noise. Airflow measurements for this heatsink were not made due to the difficulty of measuring the stock fan accurately.

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 ambient conditions during testing were 16 dBA and 26°C. This is significantly warmer than the usual lab conditions, and reflect a recent spate of hot weather. Please keep this in mind when comparing results.


Zalman CNPS8000 with Stock fan
Fan Voltage
°C Rise
Load Temp: CPUBurn for ~20 mins.
°C Rise: Temperature rise above ambient at load.
°C/W MP / TDP: Temperature rise over ambient per Watt of CPU heat, based on CPU's Maximum Power (100W) or Thermal Design Power (84W) rating (lower is better)
Noise: SPL measured in [email protected] distance with high accuracy B & K SLM

Fan @ 12V: The 40 [email protected] noise measurement says everything that is necessary about the CNPS8000 at full tilt. The heatsink is not even close to usable in a quiet system at this level. The noise was characterized by a loud whine and a significant clatter of airflow and mechanical noise. To make matters worse, the performance also left much to be desired. With the exception of the lowly $15 Arctic Cooling Alpine, every other heatsink we have tested on this test bench was cooler at a lower noise level.

Fan @ 9V: The fan was still too noisy and too whiny to be usable at 9V, and the performance numbers continued to disappoint.

Fan @ 7V: It wasn't until the fan was at 7V that we would even consider using the CNPS8000 in a quiet system, when it just barely slipped under the 30 [email protected] threshold that we consider quiet. Even then, the whine was still quite prominent, although lower in pitch than before. A significant amount of turbulence noise was also audible.

Thankfully, performance did not drop much, although we would not want to cool our 100W processor at this level. A cooler AMD chip would have a better chance at this level. The small performance drop is somewhat of an empty victory, since at this noise level most of the other heatsinks we've tested perform as well as the CNPS8000 at 12V. The CNPS8000 cooled about as effectively as the much cheaper Arctic Cooling Alpine at this noise level.

Fan @ 5V: The fan was finally quiet, though far from inaudible or silent, and its noise character still left much to be desired. It still produced a deep growling hum.

The maximum temperature of 60°C was not enough to cause our processor to throttle, although it was on the high side. Embedded in a case with a higher ambient temperature, it's unlikely that the heatsink would cool effectively at this fan speed. Once again, performance was not worth mentioning; at the 23~24 [email protected] level of noise, the CNPS8000 was thoroughly trounced by most of the other heatsinks we've tested.

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