Review: Nexus KCZ-2700 CPU Cooler

Cooling
Viewing page 2 of 2 pages. Previous 1 2

TESTING

Here's an overview shot of the testing platform:

Key Components in Socket-A HS Test platform:

AMD XP1600+ Palomino core (1.4 GHz, 1.75V, 63W, 90° C maximum core temp) - The slow clock speed is compensated by lower efficiency of the Palomino core, which gives us a CPU that puts out quite a lot of heat, even by current standards.

ABIT KT7A-R motherboard - VIA KT133A chipset, >2 years since acquisition and many generations old, still works well.

Panaflo FBA08A12L1A 80mm - Our reference fan

Maxim MAX6657 thermal monitor chip -- In a small external circuit built and provided by John Hill, once a writer for Overclockers.com. 3 leads soldered to CPU pinouts on the underside of motherboard pick up thermal diode signal from XP processor; output goes into SMBUS header on motherboard (shown here) where it can be read by MBM or other software. Accuracy is as good any XP diode monitor built into socket-A motherboards (many of which are still incorrectly implemented).

Any VGA card (AGP)

256 MB SDRAM - PC133 generic

Any hard drive in Smart Drive from Silicon Acoustics - The noise is not big a deal, but as the test platforms use noisy IBM and WD drives displaced from working PCs by Barracudas, the SD helps prevent insanity cause by whining.

DigiDoc5 w/ thermal sensors - Contributed by SVC; it helps track temp of air inflow to fan and confirm mobo readings

Any Good PSU - Usually whatever is available on the test bench that does not make too much noise. This time it was a Nexus NX-3000.

Sunbeam Rheobus fan controller -- It's easy to check the voltages (to ensure ¬Ī 5%).

Arctic Silver 3 Thermal Compound - Arctic Silver is widely regarded as the best thermal compound available. The Arctic Silver people provide detailed instructions on how to get the best of their product, and these instructions are adhered to religiously. Except for one point: They caution that it...

"...will take a minimum of 72 hours, and as many as 200 hours to achieve maximum particle to particle thermal conduction and for the heatsink to CPU interface to reach maximum conductivity. (This period will be longer in a system without a fan on the heatsink.) The CPU's temperature will drop as much as 2C to 5C over this "break-in" period."

We just can't afford that kind of time, so measurements are usually taken anywhere from half an hour to a couple of hours after application. Subtract 2C from all our temp readings if you wish.

CPUBurn is the stress program used to load the CPU to 100%. It heats up the CPU a bit more than just about any other utility tried so far (including Prime95).

Each heatsink was cleaned and installed in turn on the test system as per the manufacturers' and Arctic Silver's instructions. The system was allowed to cool between tests for ~5 minutes with a large AC domestic room cooling fan running at full speed, the airflow directed over the entire test setup.

TEST RESULTS

  • All temperatures in degrees Celsius.
  • Diode: reading from XP1600+ CPU thermal diode with Maxim external IC, recorded by Motherboard Monitor 5.
  • The ambient temperature during all testing: 21° Celsius., measured with DigiDoc thermistor ~6 inches above CPU HS and fan.

Results with fans at 12V

Model
° C - Idle, 10 mins
° C - CPUBurn, 20+ mins
Diode
Temp rise
Diode
Temp rise
KCZ-2700MS
36
15
45
24
KCZ-2700LS
39
18
52
31

Both perform well at 12V, especially higher speed model, but the noise of either is high, with an annoying whine. Neither cannot be described as quiet. The fans may indeed measure 28 and 25 dBA @ 1 meter in free air with no impedance anywhere nearby, but coupled so closely to the heatsink on the motherboard, the noise probably easily jumps 6~10 dBA.

Results with fans at 7V

Model
° C at Idle, 10 mins
° C - CPUBurn, 20+ mins
Diode
Temp rise
Diode
Temp rise
KCZ-2700MS
41
20
52
31
KCZ-2700LS
44
23
58
37

At 7V, the noise of the Nexus KCZ-2700 with either YSTech fan is considerably improved and cooling performance remains good. Still, the MS version fan at 7V whines more than the reference 80 mm Panaflo low speed fan at 12V due to its smaller size and faster RPM.

The LS version is quiet, roughly on par with the Panaflo at 7~8V. Many would consider this a very quiet HSF. Its performance is 4° C worse than the Thermalright AX7 with a 7V Panaflo or 4° C better than the Zlaman 6000cu with a 7V Panaflo.

It is interesting that the performance of the MS version at 7V is as good as the LS version at 12V.

Results with fans at 5V

Model
° C at Idle, 10 mins
° C, CPUBurn, 20+ mins
Diode
Temp rise
Diode
Temp rise
KCZ-2700MS
43
22
59
38
KCZ-2700LS
49
26
67
46

Here, we see again a match between the cooling performance of the MS version fan at 5V and the LS version fan at 7V. The noise is still higher with the MS fan at 5V than with the LS fan at 7V, however. Performance with the LS version fan is pretty questionable, however: A 46° C rise in temp is not exactly scintillating, but its noise is now just a whisper.

DATA ANALYSIS

Temp rise at 100% CPU load is probably the simplest, most useful data. If you're considering using one of these HS with a similar CPU, just add the your case ambient temp to the ° C rise and you'll get a reasonable prediction of maximum temperature in your setup. Temp (° C) rise refers to the temperature rise in ° C over ambient temperature - the difference between diode temp readings and the room ambient.

The test system's AMD XP1600+ (Palomino core) is rated to produce 62.8W maximum at the default 1.75V Vcore. All monitoring programs show the test motherboard's Vcore, set to default, to be 1.81~1.84V, slightly higher than normal. This puts the power up a bit; let's call it 65W. So the assumption is that CPUBurn working in Windows XP causes the XP1600+ to dissipate 65W.

HS cooling performance is best summarized by ° C/W or how many degrees the object temperature rises for each watt of heat it dissipates. A specification of 1° C/W means temperature rises by 1° C for each watt of heat -- this is very bad performance for a CPU HS, BTW.

Using 21° C (measured 6 inches above the fan intake) as the room ambient temp, the ° C/W calculated for each HS at each fan voltage (with the CPU at 100% load) is summarized below.

Model
12V
7V
5V
° C rise
° C/W
° C rise
° C/W
° C rise
° C/W
KCZ-2700MS
24
0.37
31
0.48
38
0.58
KCZ-2700LS
31
0.48
37
0.57
46
0.71

CONCLUSIONS

Real world conditions are tougher than those in our lab. When a system is installed in an enclosed case, the ambient temperature is sure to rise at least 5° C, more often 10° C or even more, depending on particulars. Many quiet PC enthusiasts run systems with no case fan or just one low airflow fan. In consideration of these factors, low noise enthusiasts are urged to add 10° C to the results above when trying to guesstimate what their temperatures would be. Note too, that the results here are specific to the XP1600+ Palomino.

It is best to regard the test results not in an absolute way, but rather, as comparative guidelines. The result obtained with this heatsinks will vary greatly on the particulars for each system.

The Nexus KCZ-2700 MS provides very good cooling performance with its fan at 12V, albeit at a noise level most SPCR readers are unlikely to tolerate. At 7V it is much better noise-wise and still provides good cooling performance. With a voltage controller like the Zalman Fan Mate 1 or similar, it becomes a contender.

The Nexus KCZ-2700 LS provides good cooling performance with its fan at 12V, at a noise level almost tolerable for many SPCR readers. At 7V it is very good, noise-wise, becoming competitive with the Panaflo 80L at reduced voltage. It still provides decent cooling performance. Again, with a voltage controller like the Zalman Fan Mate 1 or similar, it becomes a low noise contender.

While not the best of the quiet models around, these Nexus HSF are also not nearly as costly. They are simple to implement, compact and effective. The KCZ-2700 LS, in particular, should find favor with those who like simple, effective, no-fuss solutions. Recommended.

Great thanks and appreciation to Nexustek for the review samples and their kind support.

* * * * *

Comment on this article in our Forums.



Previous 1 2

Cooling - Article Index
Help support this site, buy from one of our affiliate retailers!
Search: