Arctic Cooling Freezer 7 Pro HSF

Cooling
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COMPARISONS

Along with the Freezer 7 Pro, three other heatsinks were tested on our new socket 775 test platform: A Scythe Ninja, a Thermalright XP-120, and a stock Intel heatsink. (The links take you back to our original reviews of these heatsinks, tested on our P4-2.8 Northwood socket 478 platform.) Both the Ninja and the XP-120 were tested with a Nexus 120mm fan, our current reference fan of that size.

REFERENCE HSFs on INTEL 520-775 TEST PLATFORM
Stock Intel HSF
Fan Voltage
Temp
°C Rise
°C/W MP
Noise
(dBA@1m)
AC Power
12V
52°C
31
0.31
34
133W
9V
59°C
38
0.38
26
136W
7V
throttle
N/A
N/A
20
141W
Scythe Ninja w/ Nexus 120 fan
12V
40°C
19
0.19
23
132W
9V
43°C
22
0.22
20
133W
7V
45°C
24
0.24
18
133W
5V
50°C
29
0.29
<17
134W
Thermalright XP-120 w/ Nexus 120 fan
12V
45°C
24
0.24
23
132W
9V
48°C
27
0.27
20
133W
7V
53°C
32
0.32
18
134W
5V
68°C
47
0.47
<17
140W
Airflow: Measured in Cubic Feet per Minute mounted on the HS
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)
Noise: SPL measured in dBA/1m distance with high accuracy B & K SLM
Throttle: CPU drops its internal voltage and clock speed to avoid thermal damage. Usually occurs at 75~76°C with this particular processor.


The other heatsinks and fans.

For the record:

  • The clips on our Thermalright XP-120 sample may have become worn over the course of many mounts and dismounts on many motherboards. It is very fiddly to mount on this 775 socket motherboard. It's difficult to tell whether cooling was adversely affected.
  • Both the Ninja and the XP-120 were also tested with an AcoustiFan AF120C Ultra Quiet Fan. At 12V, this fan is rated for 50CFM, and, more importantly, 34 dBA@1m. This happens to be about the same noise level as the Freezer 7 Pro at 12V. The SPL was confirms with our sound level meter in the lab. The cooling improved only by 1°C on the Ninja, and just 2°C on the XP-120. With the Ninja's widely spaced fins, the ~40 CFM of the Nexus 120 fan was already wringing close to maximum performance. With the more tightly spaced fins of the XP-120, perhaps greater performance improvement could be had with higher airflow. The AcoustiFan actually only provides just over 10 CFM gain in airflow over the Nexus 120.


The XP-120...


...and the Ninja were both mounted with the 478 conversion adaptors that came with the Ninja.

For your reading convenience, here's the test data on the Freezer 7 Pro from the previous page:

Arctic Cooling Freezer 7 Pro with Stock fan
Fan Voltage
RPM
Temp
°C Rise
°C/W MP
°C/W TDP
Noise
(dBA@1m)
AC Power
12V
2400
39°C
18
0.18
0.21
33~37
132W
10V
1800
47°C
26
0.26
0.31
28
132W
9V
1350
53°C
32
0.32
0.38
20
134W
8V
900
67°C
N/A
N/A
N/A
18
138W
7V
<700
throttle
N/A
N/A
N/A
<17
141W

Comparison 1: AT HIGH SPEED / NOISE

Heatsinks Compared at about the Same High Noise Level
Heatsink/Fan
Noise
(SPL - dBA@1m)
Fan Voltage
Load Temp
°C Rise
°C/W MP
AC Power
Arctic Cooling Freezer 7 Pro
33~37
12
39°C
18
0.18
132W
Scythe Ninja, AcoustiFan 120
35
12
39°C
18
0.18
132W
Thermalright XP-120, AcoustiFan 120
35
12
43°C
22
0.22
132W
Stock Intel HSF
34
12
52°C
31
0.31
133W

The Freezer 7 Pro did a great job of cooling at 12V. It blew past the stock cooler, and handily beat the XP-120 + Acoustifan 120 combo by a big 5°C margin. Only the Ninja + Acoustifan 120 combo could keep up. For overclockers and performance enthusiasts, this is very good news. This kind of cooling performance at such a modest price is a pretty amazing bargain. Both the Ninja and XP-120 sell for US$40~50 without a fan. Any 120mm fan will set you back another $10 at least. But for anyone interested in low noise, none of the above heatsink configurations are worthwhile. They are all just too loud. As for the question of better cooling for the VRM, this was not reflected in the AC power draw measurements.

Comparison 2: AT LOW SPEED / NOISE

Now, if you examine all the above performance tables, you will find that even at 12V, the Nexus fan is just 23 dBA@1m. The closest matching acoustic points for the Freezer 7 Pro are 28 dBA@1m at 10V or 20 dBA@1m at 9V. We could go back and reinstall that heatsink yet once again and run yet another test at 9.5V, but what say we fudge a little here and just split the difference in the results between 10V and 9V? We think this would be fairly representative. (If you disagree with this minor compromise, you can always rant at us in the forums.)

Heatsinks Compared at about the Same Quiet Noise Level
Heatsink/Fan
Noise
(SPL - dBA@1m)
Fan Voltage
Load Temp
°C Rise
°C/W MP
AC Power
Arctic Cooling Freezer 7 Pro*
24
9.5
50°C
29
0.29
133W
Scythe Ninja, Nexus 120
23
12
40°C
19
0.19
133W
Thermalright XP-120, Nexus 120
23
12
45°C
24
0.24
133W
* Extrapolated guesstimates. See paragraph directly above this table.

The results here are sobering. The cooling performance of the Freezer 7 Pro is fine, but it is off the pace by quite a margin. And we already know that the Nexus 120 at 12V is a bit smoother sounding than the Freezer 7 Pro fan at 9.5V. There's really no contest.

Why is there such a quick drop-off in performance compared to the Ninja and the XP-120?

The biggest significant difference, we believe, is the airflow impedance in the heatsink fins themselves. The Freezer 7 Pro's fins are very closely spaced, approximately 2mm, and the distance the air has to travel through is 58mm. It's a pretty constricted space. There really isn't that much airflow you can feel with your fingers in the center of the far side of the heatsink, even with the fan at full speed. Much of the airflow appears to come through along the perimeter of the fins, not the center. With lower fan speeds, the impedance is high enough to make a dramatic drop in cooling effectiveness.

In contrast, the Ninja heatsink fins are about 4mm apart, and even though the distance between the gaps is a long 110mm, there are deep cutaways in the corners of each fin, and a hole in the center of each fin. With the Ninja, the impedance is so low that you can feel the same airflow all around the exhaust side of the fins at any fan speed.

The XP-120 has fins as tightly spaced as the Freezer 7 Pro, but the distance the air has to travel through is no more than ~20mm for about 75% of the total area of the fins. In the very center, the distance is closer to 50cm. Again, like the Ninja, very little impedance to airflow can be felt.

All this means that the Freezer 7 Pro is really optimized for best cooling at high airflow and pressure. Its airflow-to-cooling ratio falls steeply as fan speed is reduced. Although the total cooling surface area is large, only at high fan speed (and pressure) can the airflow reach it to blow the heat way. Both the Ninja and XP-120 maintain a steadier airflow-to-cooling ratio throughout, as the airflow changes more linearly with fan speed changes.

Regarding the cooling for the VRM, again, there were no significant differences in the AC power draw measurements.

Comparison 3: AT MINIMUM SPEED / NOISE

At this near-silent level, the performance difference among the three heatsinks are the same as in the previous comparison. There is still a 10°C spread between the Ninja and the Freezer, whose performance is still acceptable for this CPU. However, this is about the limit of the Freezer 7 Pro. You cannot run it any quieter without running into overheating problems. In contrast, the Ninja and XP-120 still have room to move; they can go down to 18 dBA@1m and still have good enough cooling performance with this CPU. The Ninja, especially, has a lot more headroom; it kept temperature rise to just 23°C at 18 dBA.

Heatsinks Compared at 20 dBA@1m
Heatsink/Fan
Noise
(SPL - dBA@1m)
Fan Voltage
Load Temp
°C Rise
°C/W MP
AC Power
Arctic Cooling Freezer 7 Pro*
20
9
53°C
32
0.32
134W
Scythe Ninja, Nexus 120
20
9
43°C
22
0.22
133W
Thermalright XP-120, Nexus 120
20
9
48°C
27
0.27
133W

Regarding the cooling for the VRM, again, there were no significant differences in the AC power draw measurements. You will probably have noticed that for all the heatsinks, there appears to be a direct relationship between CPU temperature and system power draw: The hotter the CPU gets, the more power the system draws. The range between the lowest and highest power draw was 132W to 141W. Does this mean higher CPU temperature always results in poorer VRM or system efficiency? Or is it that the reduced airflow that causes higher CPU temperature also happens to provide less cooling for the VRM? If the VRM can be cooled independent of CPU temperature, will power draw still go up when the CPU gets hotter or will it stay stable? These are all questions for another article.

Finally, it's too bad that we didn't have a suitable Zalman 7000AlCu or 7000Cu model to compare against the Freezer 7 Pro on this platform. We have a couple of them in the lab, but they are older models without proper hardware for socket 775. We're pretty sure the Freezer 7 Pro would stomp all over the 7000s at the full 12V speed, but they are close in price, and at the lower, quieter fan speeds we're more interested in, they might be close competitors. Perhaps later in an update, or when we look at the Freezer 64 Pro.



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