Zalman CNPS7000-Cu

Low noise heatsink with very good cooling performance – Joe

SUMMARY: Can be run whisper quiet with decent cooling, or merely quiet with very good performance.

CNPS7000-Cu

The good guys at The Heatsink Factory were nice enough to send a sample of Zalman’s CNPS7000-Cu. This is one of the more interesting and very nice looking P4 heatsinks I’ve seen. Designs which feature “enclosed” fans tend to be very efficient and less noisy.

The fan used is 92mm, which gives some idea of its size – it measures 109mm diameter x 62mm high and weighs 773 grams. Check Zalman’s site for motherboard compatibility and a well done video demonstrating installation.

Zalman includes a rheostat

Rheostat

with this unit which allows users to dial in fan speeds. The problem I see with it is that it’s not designed to mount in a readily accessible location – unless you intend to run your case without a side panel, adjusting fan speeds will require removal of the case’s side panel. This is fine if you intend to “set it and forget it”, but for continually tuning fan rpms, it’s not too handy.

At its lowest and highest setting, I could not measure fan noise with a Radio Shack sound meter¹ 8″ from the fan; at its lowest, it’s virtually silent.

The base is formed by compressing the fins with two bolts:

Base

The base is then polished to a flat finish – I found it to be very well finished and doubt that hand lapping will improve it.

The mounting mechanism is a good one:

Clip

The long brackets slip into the P4 retention bracket and, using two screws, the heatsink bolts into the brackets. I found it fairly easy to mount, as long as your handy with a magnetic screwdriver. In additon, there are two “nipples” for AMD Athlon 64 CPUs.

THE TEST

I tested the Zalman CNPS7000-Cu on an Acorp 4S845A motherboard with a modified P4 1500 to read CPU case temps.

TEST RESULTS – Motherboard
Motherboard
CPU Case Temp

Ambient Temp

Delta

C/W

MBM Temp

Zalman, 1360 rpm
34.4 C

22.2 C

13.2

0.23

30 C²

Zalman, 2211 rpm
31.8 C

21.2 C

10.6

0.18

27 C²

² MBM Temps as measured by the P4′s on die diode.

Delta = CPU temp – Ambient Temp
C/W = Delta / CPU Watts

Interpreting C/W: For every watt (CPUw) that the CPU
consumes, the HSF will limit the CPU’s temperature rise to (C/W x CPUw)
plus the temperature at the HSF’s fan inlet. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that CPU temp will increase 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.

Motherboard results place the Zalman CNPS7000-Cu, at its quietest setting, in the mid rank of P4 heatsinks (Heatsink Ranking) tested to date. At its highest setting, it ranked near the top.

CONCLUSIONS

As always, less noise = less cooling. However, the Zalman CNPS7000-Cu can run whisper quiet delivering decent performance and quiet delivering very good performance. Overall, the Zalman CNPS7000-Cu looks like an excellent design balancing low noise with very good cooling.

Thanks again to The Heatsink Factory for sending this our way.

¹Note that manufacturers measure fan noise usually 3 feet from the fan, resulting in lower dBA readings.
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Email Joe

SUMMARY: Could be adapted for very good Socket A cooling.

CNPS7000-Cu

The good guys at The Heatsink Factory were nice enough to send a sample of Zalman’s CNPS7000-Cu.

It seems that a number of folks have adapted this heatsink for Socket A use – the “Dark Stalker” sent me this link to an article (in Danish – thanks Axle!) which shows how it’s done. In addition to building mounting brackets, the base may need modification to seat properly on the CPU.

Being of curious mind, I decided to see how the Zalman CNPS7000-Cu might fare as a Socket A heatsink.

THE TEST

The Zalman CNPS7000-Cu was tested on the Socket A CPU Die Simulator which gives results that are unaffected by motherboard influences. I also tested it without the fan controller – it increased fan speed by about 200 rpm.

TEST RESULTS – CPU Simulator

Heatsink
Die Temp
Ambient Temp
Delta
C/W
Zalman CNPS7000-Cu, 2632 rpm, 74.7w
44.0 C
20.1 C
23.9 C
0.32
Zalman CNPS7000-Cu, 2441 rpm, 74.7w
44.8 C
20.0 C
24.8 C
0.33
Zalman CNPS7000-Cu, 1356 rpm, 74.7w
49.9 C
20.1 C
29.8 C
0.40

Delta = CPU temp – Ambient Temp
C/W = Delta / CPU Watts

Interpreting C/W: For every watt (CPUw) that the CPU
consumes, the HSF will limit the CPU’s temperature rise to (C/W x CPUw)
plus the temperature at the HSF’s fan inlet. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that CPU temp will increase 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.

Die Simulator results place the Zalman CNPS7000-Cu, at its highest fan speed, in the upper rank of Socket A heatsinks tested to date (Heatsink Ranking).

CONCLUSIONS

All things considered, the Zalman CNPS7000-Cu is shaping up to be a fine choice for very good cooling at reasonable noise levels. Reducing fan rpms can reduce noise to a whisper, but cooling performance will suffer. With an easily accessible variable controller (eg a rheobus), this is a heatsink that won’t keep you up at night.

Thanks again to The Heatsink Factory for sending this our way.

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