Review: Thermalright SP94, SP97 & other heavyweights

Cooling
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TESTING

The testing for this article took place over many days. As stated earlier, the article incorporates a great many tests and measurements. Each test was run at least twice, sometimes three or four times when the results seemed unlikely. In most cases, the numbers posted here were obtained almost every time. In cases where there was more variance, it was rarely more than by 1°C, for which the numbers that best fit a trend were selected for final posting here, or an average was used.

P4 HS TEST PLATFORM

The P4 HS test platform is an open system not enclosed in a case. The test platform and procedure is described in detail in our HS Test Methodology article, but there have been some changes, which are noted below.

  • Intel P4-2.8A This is a change from the ~50W P4-1.8A used in previous P4 reviews. Given that the current fastest P4s are 3.2GHz running 800 MHz bus, it was time for a hotter and faster CPU. 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.
  • Intel D845PEBT2 motherboard - Intel 845PE Chipset; on-die CPU thermal diode monitoring
  • Panaflo FBA08A12L1A 80mm DC fan
  • Any VGA card (AGP)
  • 256 MB DDRAM
  • Any hard drive (in Smart Drive from Silicon Acoustics)
  • DigiDoc5 w/ thermal sensors
  • Any Good PSU
  • 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

Please read the caveats about P4 thermal diode accuracy on page 2 of the HS test methodology article. There is evidence to indicate the diode might read >10°C lower than actual core temperatures. At this time, we use the thermal diode to obtain CPU temperature information -- like the vast majority of hardware sites. Other options, such as Intel's P4 Thermal Test Vehicle (discussed in this Intel PDF document), are still being investigated.


Here's the P4 system set up with the threaded through-board anchors for the heatsink.


The steel reinforcing plate on the underside of the motherboard.


Image from above showing two of the spring-loaded bolts.


Reference Panaflo 80L fan placed (not clipped) on SP94, ready for testing.

Reference Panaflo Fan Summary

Table 1: Panaflo FBA08A12L1A Speed, Airflow and Noise
VDC
12V
9V
7V
5V
RPM*
1880
1520
1230
760
dBA @ 1m**
21
17
12
10
CFM**
24
19
14
9

* RPM was measured on two Panaflo samples using MBM5 along with a custom-made tachometer board provided by Fan Control, an electronics-savvy member of the SPCR Forum. This allows accurate readings of fan speed down to much below 1000 rpm, which is usually not possible with standard on-board sensors. The readings from the two fans were averaged for the above table.
** Both dBA@1m noise and CFM (cubic feet per minute) airflow figures are extrapolated from the 12V manufacturer's specifications. Please see the Excel table by gmJamez in the article Choosing Fans for Quiet, High Airflow: A Scientific Approach.

Table 2: Panaflo FBA08A12L1A Description of Perceived Noise
Note that the description below refers to the best samples of this fan. There are some variations from batch to batch, generally less than many other brands and models.
12V
Plainly audible from several feet away. Some low frequency vibration can be heard and felt; direct mounting to a chassis accentuates the low frequency noise. Most audible aspect of sound is centered around 5-10 KHz; whine and whoosh are best descriptors. Much quieter and smoother sounding than most commonly used fans.
9V
Noise is substantially reduced. Its overall character is not changed, but the 5~6 dBA/1m decrease may be enough in many cases to put the level below the overall noise level of the PC system (thus making in inaudible) in a less than quiet environment (~30 dBA).
7V
All aspects of noise are greatly diminished. From a couple feet away, it is inaudible to many people, even in a very quiet room. Qualitatively, it is a hum rather than a whoosh or whine. No high pitched noise at all. Enough vibration remains that direct chassis mounting produces a bit of low frequency accentuation.
5V
Essentially inaudible in free air except from under one foot distance. Someone with higher hearing sensitivity might hear it from 2 feet, but it would only be a whisper, or rather a very quiet buzz. The vibration level is low enough that direct chassis mounting produces no significant boost in low frequency noise.

Test Procedures

  • Temperatures were taken after 20 minutes of CPUBurn.
  • The system was allowed to cool between tests for ~15 minutes. The ambient temperature was 20C throughout.
  • All temperatures in degrees Celsius.
  • Diode: reading from P4-2.8 CPU diode via Intel Hardware Monitor.
  • Temp Rise refers to the difference between ambient temperature and the diode reading. The ambient temperature during all testing: 20? Celsius., measured with an external thermometer ~6 inches above CPU HS and fan.
  • °C/W refers to the number of degrees of temperature rise per watt of heat dissipated by the CPU. As mentioned above, we'll use 69W as the CPU heat. If the power dissipation is correct, °C/W can be used to accurately predict the performance of the HS with processors of different wattage.
  • To estimate temperatures inside a PC case, add a minimum of ~10°C to the room temperature. The case temp rise can be less or more; this varies on so many factors that it is difficult to be more specific.
  • The idle temps are not reported because the highest was only 29°C.
  • The performance with the Panaflo at 5V were not reported because of the limited cooling usefulness at that voltage (all temps were above 60°C), the time required for all this testing, and the fact that in the vast majority of cases, the difference between the Panaflo at 7V and at 5V is negligible.

PERFORMANCE: SP94

Table 3: SP94 on P4-2.8
Panaflo 80L fan
Diode
Temp rise
° C/W
12V
44°C
24°C
0.35
9V
47°C
27°C
0.39
7V
55°C
35°C
0.51

Regular readers will complain that these results are not directly comparable to previous P4 heatsink tests at SPCR, and they will be right. In anticipation of such complaints, heatsinks tested in the past with the P4-1.8 were pressed into service here. These include the SLK900 and both aluminum/copper as well as all-copper versions of the Zalman 7000.

The Zalman 7000 heatsink poses a challenge to a rational comparative method. Its integrated fan differs substantially from the reference Panaflo:

Table 4: Panaflo vs Zalman 7000 fan
Model
Size
Noise
RPM
12V
5V
12V
5V
Panaflo 80L
80mm
21 dBA
9 dBA
1900
760
Zalman 7000
92mm
25 dBA
20 dBA
2400
1300

We can only guess that the airflow is at least 50% greater than that of the Panaflo. In the end, the real criteria for us is noise, so... Careful listening and confirmation with a lab-grade sound level meter showed that that noise level of the Zalman at 5V was similar in level to the Panaflo at about 9V. This was confirmed by several listeners. The noise did not sound the same, but with both, the predominant noise was that of rushing air "whooshing". In any case, our approach is that comparing the Zalman 7000 at 5V to other HS with Panaflo 80L at 9V is reasonably fair: They sound about the same.

COMPARISON: SP94 vs Others

Table 5: Just the Thermalrights
Panaflo fan
SP94
SLK900U
Temp
° C/W
Temp
° C/W
12V
44°C
0.35
44°C
0.35
9V
47°C
0.39
48°C
0.40
7V
55°C
0.51
56°C
0.52

Table 6: Just the Zalmans
Fan Voltage
Z7000alcu
Z7000cu
Temp
° C/W
Temp
° C/W
12V
36°C
0.23
37°C
0.24
9V
39°C
0.28
39°C
0.28
7V
41°C
0.30
42°C
0.32
5V
45°C
0.36
46°C
0.37

Table 7: SP94, SLK900, 7000A(alcu), 7000A(cu)
Panaflo
SP94
SLK900
Z7000alcu
Z7000cu
12V
44°C
44°C
(fan at 5V)
9V
47°C
48°C
45°C
46°C
7V
55°C
56°C
-
-

So what do tables #5, 6 and 7 above really tell us?

1) The SP94 and SLK900 appear to be very close in performance with this CPU. The SP94 seems to have a tiny edge as airflow is reduced, and although 1°C is is within the testing setup's margin of error, the difference came up the same repeatedly. Suffice it to say that for low noise cooling performance, both are excellent.

2) As in the previous full review of the Zalman HS, the all-copper version is slightly edged out in performance by the aluminum/copper hybrid. Whether this is due to the fan on the latter being slightly more efficient is hard to say, but again, 1°C is within the testing setup's margin of error.

3) The Zalman 7000s appear to perform slightly better than SP94 -- at the established noise level. This result has to be regarded with caution. The Zalman has an integrated fan that probably maximizes the available airflow, while it's possible that a different fan could produce a bit more airflow at the same noise as the Panaflo at 9V (and Zalman at 5V). If so, then the performance of the SP94 would be a higher than seen here.

4) Another consideration is that for some users, a Panaflo at 9V or the Zalman at 5V are both too loud. For users who seek a level of noise lower than that afforded by the Zalman 7000 heatsinks at 5V, the practical solutions is a heatsink without an integrated fan, like the SP94 plus a quieter fan like the Panaflo 80L at a lower voltage. Few fan controllers provide voltages below 5V.



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