CoolerMaster Aero4

Interesting design, lots of flexibility – Joe

SUMMARY: CoolerMaster’s AERO4 spans a wide performance range, from very good to very poor.


Fan: Adjustable 1900 to 3500 rpm, 11 to 20 cfm; Size: 83 x 70 x 46 mm.

The good guys at Pham Computer were nice enough to send a sample of CoolerMaster’s latest P4 heatsink, the Aero4. Included with it is a rheostat which varies fan speeds from “1900 to 3500 rpm”; it includes both a PCI slot and floppy slot cover mount for convenient adjusting.

This heatsink features a “squirrel cage” (blower) fan:


This fan takes air in from both sides and directs it to the heatsink’s base without interference from a fan hub located above a center of the heatsink found in “traditional” fans – a purported advantage. I also like the decal in lieu of a fan grill.

The base is not all that well finished:


I could easily fill machining marks on it – this is one heatsink where lapping will improve performance – perhaps 1-3 degrees better than tested.

The clip uses the standard P4 retention bracket – I found it easy to mount and very secure.


I tested the AERO4 on an Acorp 4S845A motherboard with a modified P4 1500 to read CPU case temps.

TEST RESULTS – Motherboard


CPU Case Temp

Ambient Temp



MBM Temp

Aero4, 3563 rpm, 65 dBA

38.7 C

27.6 C



36 C¹

Aero4, 2700 rpm, 58 dBA

41.0 C

27.3 C



39 C¹

Aero4, 1818 rpm, <50 dBA

45.3 C

28.3 C



42 C¹

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 Aero4, at its highest speed, in the upper rank of heatsinks (Heatsink Ranking) tested to date. At its lowest speed, the Aero4 places in the lowest ranks.


CoolerMaster’s AERO4 spans a wide performance range, from very good to very poor (a 10 C difference) – not totally unexpected, considering the iron-clad relationship between airflow and cooling performance.

For users with occasional high performance cooling, the AERO4 could be a good choice – it is virtually silent at its lowest setting and, with a P4 at idle, it will do a fine cooling job (almost anything will). For “average” use, mid-speed should be OK. Lapping the base should yield better results, if you’re so inclined.

Thanks again to Pham Computer for sending this our way – an interesting heatsink.

¹Note that manufacturers measure fan noise usually 3 feet from the fan.

Email Joe