Nexus PFT-3600 P4 Cooler

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The PFT-3600 is a P4 Cooler with a 70mm fan skivved from a single piece of aluminum. Compact, light and easy to install, it is from Nexus, one of quiet computing’s few truly well-established brands. Read the Nexus PFT-3600 review here.

October 2, 2004 by Jeremy Noring with Mike Chin

Product

Nexus PHT-3600 heatsink/fan for Socket 478

Supplier
EndPCNoise
Current Price
US$30

Nexus is a brand focused on quiet components and has produced a number of winners in the past. among them the Nexus NX-3000 and NX-3500 power supplies, and the "Real SIlent" line of fans — which really are very quiet. It’s probably not well known, but the Nexus folks have been involved in quiet computing products for a long time; they were behind the creation of the first quiet PSU brand, Q-Technology. For some time time, Nexus has offered a wide range of quiet PC products: PSUs and fans, cases and damping materials, accessories and heatsinks.

SPCR previously reviewed another integrated heatsink/fan by Nexus, the KCZ-2700. That model proved to be a simple, cost effective, compact unit with decent noise levels and a conservative design. The Nexus PHT-3600 appears to be a more robust cooling solution that may lend itself to silence more than its little brother.


Nexus PHT-3600


Nexus PHT-3600 mounted

The PHT-3600 is an all-aluminum heat sink equipped with a 2400 RPM, 70mm fan, which according to Nexus produces 19 dB. The use of a 70mm is a bit odd given that Nexus has a wonderful 80mm fan with excellent cooling properties, the Nexus "Real Silent" case fan. In addition, smaller fans generally emit more high frequency noise than larger fans, so a bit of skepticism from a silencing perspective should be expected.

According to Nexus, the V-shaped fins are supposed to optimize airflow and prevent "air obstruction", resulting in a stable RPM level and low noise operation. The Nexus says the PHT-3600 is skivved from a single piece of aluminum:

"…one of the worlds most advanced technologies. This concept permits the production of heat sinks with a precise and super fine detail previously considered impossible. SkiveTek ® represents a process of shaping materials to produce lightweight, high fin density thermal solutions. Base plate and fins are constructed out of one piece of pure aluminum or copper by cutting the material into thin layers, bending the fins in place. No bonding, welding, soldering or adhesive is involved. The joint between fin and base is continuous aluminum or copper."

This technique has been used by other brands with not only aluminum but also copper, but invariably the proof is in the pudding.

One positive aspect of the PHT-3600 is its relatively compact size and low weight. At 370 grams, it easily meets the Intel limit of 450 grams. It also has a very simple, easy to use clip that requires no tools for installation. Lastly, included with the heatsink is a cable (with an inline resistor?) to drop the fan voltage to 10V, the NRC1000:


Nexus NRC1000 10V cable

The speed reduction cable is a nice touch, although I would have preferred something that enables variable voltage settings, like the Zalman FanMate.

NEXUS SPECIFICATIONS

Model Name: PHT-3600
For: Intel Pentium 4 (socket 478) all speeds
Fan Dimensions: 70 x 70 x 25 mm
Heatsink Dimensions: 75.8 x 65 x 45.2 mm
Combined Dimensions: 75.8 x 79 x 70.2 mm
Fan Speed: 1930~2400rpm (+- 10%, using included 10V cable)
Fan Noise Level: 19 dBA; lower using included 10V cable
Weight: 370g with fan

TESTING

The PHT-3600 was installed and tested on Mike Chin’s standard P4 heatsink testing rig, described in past HS reviews:

  • 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.
  • Intel D845PEBT2 motherboard – Intel 845PE Chipset; on-die CPU thermal diode monitoring
  • Panaflo FBA08A12L1A 80mm DC fan
  • nVidia GF400MX VGA card (AGP)
  • OCZ DDRAM PC-3700, 512 MB
  • Seagate Barracuda IV 40G 1-platter drive (in Smart Drive from Silicon Acoustics)
  • Enermax UC-A8FATR4 multifunction monitor/fan controller w/ thermal sensors
  • Seasonic Super Tornado 300 (Rev. A1)
  • Zalman Multi-Connector (ZM-MC1) and Fanmate1 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.
  • CPUBurn processor stress software
  • Intel Active Monitor and Motherboard Monitor software to show CPU temperature

The ambient temperature in the test lab was 22°C. Ambient noise in the lab was ~21 dBA. For the acoustic testing, the HSF was moved to a quieter room which measured ~16 dBA. Maximum load temperatures were recorded 30 minutes into a CPU stress test with CPUBurn.

Since the PHT-3600 doesn’t have mounts for an 80mm fan, it could not be tested with the SPCR reference fan, the Panaflo 80L. The only fan used was the stock 70mm fan. The PHT-3600 was tested at four fan settings, including the 10V NCR1000 cable. The noise was measured separately with the HSF in a quiet room with no other equipment running at all. Note that by itself in free air, the fan’s noise drops by 1~2 dBA at lower speeds and 3~6 dBA at high speeds.

VOLTAGE
Idle
Folding
CPUBurn
CPUBurn Temp. Rise
° C/W (MP)
dBA / 1m
12V
(2360 RPM)
40
44
51
29
0.37
30
10V
(w/ NCR1000, 1900 RPM)
42
48
55
33
0.42
28
9V
(1800 RPM)
43
49
57
35
0.44
27
7V
(1300 RPM)
53
61
75
43
0.54
26
* All temperatures in ° C
* Note that ° C/W was calculated only on the basis of the higher Maximum Power estimate.

The first thing that comes to mind when interpreting the above results is that something is amiss concerning the 19 dBA claim by Nexus — even at 7V, we measured 26 dBA. This discrepancy is too much to ignore, even taking into account that the Nexus claim could be a measurement of the fan in free air rather than attached to the heat sink where turbulence affects the sound levels. The cooling performance worsens as the voltage drops, even approaching thermal overload in CPUBurn at 7V. This might be a result of the tight spacing of the fins, which could provide high impedance to airflow. It could also be an out-of-spec or damaged fan, but there are no obvious signs of bearing damage.

The fan has a sort of clatter reminiscent of the little fans one often finds on video cards. It’s not smooth and constant like a Panaflo 80L, but more of a solid drone at 12V. At lower speeds, it is quite a bit more relaxed, but still has sort of a puttering noise and a mild high pitched whine. Comparatively speaking, the Panaflo has a very quiet, homogenous sound to it at 7V, and no clatter to speak of. We would have much preferred to see the Nexus 80mm fan on this heatsink, as that fan is something of a noise champ.

LISTEN TO THE FANS!

You can actually hear the noise of the PHT-3600 for yourself and compare it to the Panaflo 80L (mounted on a heatsink) with the MP3 files below. These recordings were made with a high resolution studio quality digital recording system assembled specifically for recordings of quiet computer gear. The recording system and the methodology used will be covered in detail in a forthcoming article.

For now, suffice it to say that the recording microphone is always 3" from the edge of the fan frame at a 45° angle, facing the intake side of the fan and just out of the high turbulence area to avoid direct wind noise. The background noise during all recordings is 17 dBA or lower. The input level settings of all the recordings are absolutely identical, so the differences between noise sources is retained with very high fidelity. The files themselves are mono, 44kHz/16-bit with 96kbps compression. Most recent vintage music playback software should have no trouble with these files.

The better your audio playback system, the more accurate the sound reproduction and comparisons of different noise sources will be. However, even with a modest PC sound system, it is possible to get a reasonably good idea of the differences between noises. The key is to calibrate your playback system to the correct volume level.

Audiophiles and those involved in music recording are aware that truly accurate reproduction requires playback at the same volume level as the original sound. There is a way to calibrate your playback system to the correct volume level for SPCR’s noise recordings. To do this, you must have a Panaflo 80L, our reference fan, and a way to run it outside the PC at 12V.

Calibrate your Sound Playback System

  1. Hook up the Panaflo 80L fan to a 12VDC source and place it right next to a speaker. Preferably, the fan should be on a soft padded surface to minimize vibration couple effects.
  2. Turn the fan on and listen to it for a minute.
  3. Now download, save and play this reference file of a Panaflo 80L (Panaflo 80L 12V Reference MP3) in free air, driven by 12VDC. Like all the other sound files, it is 15 seconds long. Set your playback software to repeat loop if you want to listen to it for longer than 15 seconds without hitting play over and over again.
  4. Adjust the playback level of your sound system until it matches (as closely as possible) the sound level of the actual Panaflo fan next to the speaker. (You must also turn off all special sound effects, and set equalizer / tone controls to neutral or flat.) You may find this easier to do while listening to each sound by itself; simply switch the fan off while listening to the sound file and stop or mute the sound recording when listening to the fan. Once the levels are matched, do not touch the playback level settings. You may wish to record these settings for future reference.
  5. Now, your sound playback system is calibrated for level. The Panaflo 80L sound file will be played back at the level it was when recorded, as will all other SPCR MP3 sound files. If you have a very high fidelity sound playback system, these MP3 files will be the next best thing to having the actual various noise-making PC components we review in your own room to listen and compare for yourself.

NOTE: The Panaflo 80L 12V Reference MP3 is not the same as the Panaflo 80L on HS @ 12V file. The reference Panaflo 80L file was recorded in free air, driven by 12VDC. The Panaflo 80L on HS files were recorded at the indicated drive voltage while mounted on an Alpha 8045 heatsink. This is to ensure a fair comparison between the Nexus HSF and a HS equipped with a Panaflo 80L. Any fan in free air is quieter than when it is mounted on a heatsink. The close proximity of the heatsink — or any obstruction (impedance) — to a fan’s spinning blades causes air turbulence which adds to the overall noise. By mounting the Panaflo on the Alpha heatsink, both fans are operating against an impedance; hence it is a fair comparison.

If you don’t have a Panaflo 80L fan, listen to the quietest of the above sound files (the Panaflo 80L at 7V), set the playback volume to the point where it is just barely audible a meter away, and don’t touch the volume setting when you listen to any of the other files. That will be reasonably close to the actual recorded sound levels.

Finally, if your computer makes enough noise to drown out the Panaflo 80L fan 12V, you probably have little choice but to listen over the headphones, setting the level to where the quietest fan noise file can be heard comfortable, and then not resetting the volume. On the other hand. you probably should stop listening to these MP3s and just get cracking on making that PC quieter before your hearing suffers!

FINAL CONCLUSIONS

While the Nexus PHT-3600 certainly isn’t a bad heatsink, there also isn’t anything really exceptional to say about it. It has decent cooling properties, as well as adequately low noise, but doesn’t really shine in any particular scenario. We were not able to confirm the claim of 19 dBA, or even come within seven dBA of it. Taking into consideration the cost of the PHT-3600, there isn’t a compelling case for a strong recommendation.

On the other hand, the heatsink is very compact — anyone working with tight space considerations should probably have a close look at the PHT-3600. Its relatively light weight also is a plus if transportation of the computer is a frequent occurrence. Lastly, the included 10V cable is a welcome addition to any heatsink marketed as a silent solution.

Pros

* Decent performance regarding cooling and silence

* Simple design
* Small overall dimensions
* Low weight

* Easy installation – no tools required

Cons

* Cost? More effective heatsinks for similar or less $$
* 19 dBA claim is probably unrealistic
* 70mm fan really not up to snuff

Much thanks to Nexus Technology and EndPCNoise for the PHT-3600 sample.

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