Zalman CNPS5700D-Cu

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Low noise heatsink – Joe

SUMMARY: Can be run very quietly with modest cooling, or with somewhat more noise for better performance.

CNPS5700D-Cu

Footprint: 6″ x 4½” x 5″; Weight: 500 grams (both with duct).

The good guys at The Heatsink Factory were nice enough to send a sample of Zalman’s CNPS5700D-Cu. This is one of the more interesting (and large!) P4 heatsinks I’ve seen – this one features a hood to direct airflow – it’s movable so it can be oriented in any direction you choose (note that the fan pulls air up through the heatsink).

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 setting, I could not measure fan noise with a Radio Shack sound meter¹ 8″ from the fan – it’s almost silent, and in a case, I doubt you would hear it. At the high setting, it’s 57 dBA, moderately quiet but noticeable.

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. However, a closer look

Base Close

reveals gaps in the base – this appears due to the manner by which the fins are bolted together. Further, not all of the P4’s IHS is covered by the heatsink’s base, which may compromise performance.

The mounting mechanism is a good one:

Clip

One side is fixed and the other is articulated. I found it one of the easiest to mount in the standard P4 retention bracket – a very nice design.

THE TEST

I tested the Zalman CNPS5700D-Cu on an Acorp 4S845A motherboard with a modified P4 1500 to read CPU case temps, and the P4 Simulator.

TEST RESULTS – Motherboard
Motherboard

CPU Case Temp

Ambient Temp

Delta

C/W

MBM Temp

Zalman, 1633 rpm

41.2 C

21.1 C

20.1

0.35

30 C²

Zalman, 3056 rpm

35.1 C

20.9 C

14.2

0.25

26 C²

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

TEST RESULTS – P4 Simulated Die
Heatsink

Die Temp

Ambient Temp

Delta

C/W

Zalman, 1660 rpm, 79.6w

48.5 C

20.3 C

28.2

0.35

Zalman, 3125 rpm, 79.6w

41.4 C

21.0 C

20.4

0.26