Zalman CNPS7700-AlCu Heatsink/Fan

Cooling
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TESTING

The core of the test system is similar to that used in the past, but not identical.

The motherboard has been changed because the venerable Intel D845PEBT2 motherboard used for over two years finally petered out. It survived more than 200 HSF mount/dismount procedures, and probably 50 CPU changes; it's a miracle the board lasted as long as it did. The replacement is another Intel 845 chipset motherboard which has seen only a dozen or so HSF changes. Its CPU thermal monitoring has been calibrated to be within 1°C of the Intel board it replaced.

Test Platform

  • Intel P4-2.8A The Thermal Design Power of this P4-2.8 (533 MHz bus) is 68.4 or 69.7W depending on the version. As the CPU is a demo model without normal markings, it's not clear which version it is, so we'll round the number off to ~69W. The Maximum Power, as calculated by CPUHeat & CPUMSR, is 79W.
  • AOpen AX4GE Max motherboard - Intel 845GE Chipset; built-in VGA. The on-die CPU thermal diode monitoring system reads 2°C too high, so all readings are compensated up by this amount.
  • Panaflo FBA08A12L1A 80mm DC fan
  • OCZ DDRAM PC-3700, 512 MB
  • Seagate Barracuda IV 40G 1-platter drive (in Smart Drive from Silicon Acoustics)
  • Seasonic Super Tornado 300 (Rev. A1)
  • Zalman Multi-Connector (ZM-MC1) and Fanmate2 voltage controller
  • Arctic Silver Ceramique Thermal Compound
  • Two-level plywood platform with foam damping feet. Motherboard on top; most other components below. Eases heatsink changes and setup.

Measurement & Analysis Tools

  • CPUBurn processor stress software
  • Motherboard Monitor 5 software to monitor CPU temperature
  • Enermax UC-A8FATR4 multifunction monitor/fan controller w/ thermal sensors
  • T.H.E. KP- 6M reference omni microphone
  • M-Audio Tampa mic preamp
  • M-Audio Firewire 410 external digital sound interface
  • B&K 2203 sound level meter
  • SPCR lab custom-built multi-channel variable DC power supply
  • Digital display multimeter
  • Digital display anemometer to measure fan airflow

The ambient temperature in the test lab was 21°C. Ambient noise in the lab was ~20 dBA most of the time. When measuring quieter fans, all unnecessary systems were turned off so that the ambient dropped to ~18 dBA. Supplementary SPL measurements were also conducted in a quieter, larger room with a lower 16 dBA noise floor. Maximum load temperatures were recorded >20 minutes into a CPU stress test with CPUBurn.

RESULTS

Zalman CNPS7700-AlCu
Fan Voltage (V)
Airflow (CFM)*
SPL (dBA/1m)
Load Temp (°C)
°C Rise from ambient
°C/W MP
°C/W TDP
12
32
38
39
18
0.23
0.26
9
25
32
41
20
0.25
0.29
7
18
28
43
22
0.28
0.32
5
12
22
46
25
0.32
0.36

*CFM (cubic feet per minute): Measured with the fan on the heatsink, with heatsink mounted on the CPU. (+/- 10%)
SPL: Sound Pressure Level in dBA/1m measured with high accuracy B & K SLM at 1 meter
Load: CPUBurn for ~20 mins
°C Rise: Temperature rise above ambient at load
°C/W MP / TDP: Temperature rise per Watt, based on Maximum Power (79W) or Thermal Design Power (69W) rating of CPU

* Why was airflow measured with the fan on the installed HS?

We wanted to make fair comparisons of this HSF against separate HS + fan combinations . Because the fan in the 7700 is frameless, when held in free air, its flow is not as directed as a normal box frame fan; hence its CFM measures very low. But both the 7700 fan and a framed fan can be measured mounted on the HS, which provides the best apples-to-apples comparison, and in-use conditions. From a performance point of view, the HS that cools best with lower airflow is the better one.

Performance at 12V is excellent, as expected. The noise measures higher than specified by Zalman, and it is louder than most SPCR readers would accept. This, too, is expected. Overall, the acoustic signature is benign. There is mostly whooshing wind turbulence and no bearing noise to speak of.

At the 9V fan drive level, the noise has dropped nicely but is still a bit loud. Performance is still excellent. Ditto at 7V, but it's still not really quiet enough for SPCR.

It's at under 6V that the fan noise comes down to a level most SPCR readers would accept. The 5V performance is still very good, and it is very quiet at this point. There is evidence of low frequency hum and a touch of buzzing, but inside a case with other noise producing components, it would be pretty hard to hear.



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