Speeze 5F263B1M3

Low noise, low performance – Joe

SUMMARY: Low noise, low performance – not for aggressive cooling.


The good guys at Speeze were nice enough to send over a sample of their Socket A/370 heatsink, the Speeze 5F263B1M3. This is an aluminum extrusion unit with a fairly quiet fan.

The fan is a FTC (Fanner Tech) Model # FD08025B1M – an 80 x 25mm unit rated at 38 cfm @ 2700 rpm, 27 dBA¹. I found it to be very quiet – I measured its noise at 50 dBA with a Radio Shack sound meter 8″ from the fan’s intake, substantially less than a Delta 38 (about 69 dBA). It’s also safe to use a motherboard fan header – 1.6 watts.

Note that the fan’s body is aluminum – not plastic.

The base is not particularly well finished:


When I ran my nail over it, I could feel and hear ridges.

The clip requires a screwdriver to mount on the socket and is not particularly stiff.

In summary, an low noise, extruded aluminum heatsink.


The Speeze was first tested on the CPU Die Simulator which gives results that are unaffected by motherboard influences. I then tested it on a Shuttle AK31, modified to read AMD’s on-die diode, as an example of what users might see on their systems.


Die Temp
Ambient Temp
Speeze, 2780 rpm
52.6 C
22.1 C
30.5 C

TEST RESULTS – Motherboard

CPU Die Temp

Ambient Temp



CPU Temp

XP @ 1467, Shuttle AK31

58.4 C

24.1 C



42¹ C

¹In-socket thermistor per MBM

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 Speeze in the lower rank of heatsinks tested to date (Heatsink Ranking).


No such thing a free lunch – low noise cooling solutions trade off performance, although I think in this case a stiffer clip would increase performance a bit. OK for Mom.

Thanks again to Speeze for sending this our way.

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

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