Very good P4/Socket A heatsink, depending on noise preferences – Joe

SUMMARY: A very good heatsink for P4 or Socket A use.


Size: L96 x W86 x H45 mm; Weight: 570 grams.

The good guys at The Heatsink Factory were nice enough to send us a sample of Thermalright’s 947-U. This is the usual all-copper construction we’ve seen from Thermalright; in addition, this unit is designed for both P4 and Socket A use.

The base is a copper baseplate:


I could feel very slight ridges as I dragged my fingernail over it.

The 947-U ships with a bundle of parts:


There are mounts to use Intel’s retention bracket and spring-loaded bolts for bot Socket A and P4 mouting. Fan clips are included for 60, 80 and 92 mm units.

Overall, the build quality is very good.


The Thermalright 947-U was tested on an Acorp 4S845A motherboard with a modified P4 1500 to read CPU case temps; for Socket A, I used the CPU Die Simulator. For testing, I used a Delta FFB0812SHE, 68 cfm @ 4800rpm, 48.5 dBA; this features vanes in the base which straighten airflow into the heatsink. I varied rpms to give a range so users can match performance to noise tolerance.

P4 TEST RESULTS – Motherboard

CPU Case Temp

Ambient Temp



MBM Temp

Acorp 4S845A, 4840 rpm, 69 dBA²

32.0 C

22.5 C



28 C¹

Acorp 4S845A, 3523 rpm, 60 dBA²

34.1 C

23.8 C



30 C¹

Acorp 4S845A, 2021 rpm, <50 dBA²

38.6 C

25.0 C



35 C¹

Socket A TEST RESULTS – CPU Simulator

Die Temp
Ambient Temp
4816 rpm, 69 dBA²
42.6 C
24.4 C
18.2 C
3512 rpm, 60 dBA²
44.9 C
24.8 C
20.1 C
2010 rpm, <50 dBA²
50.4 C
25.2 C
25.2 C

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 Thermalright 947-U in the upper rank of P4 heatsinks and in the upper rank of Socket A heatsinks (Heatsink Ranking) tested to date.


Performance, as usual, is dependent upon how much noise you’re willing to tolerate. Thermalright’s 947-U is a heatsink for all flavors – P4 or Socket A. Featuring myriad mounting hardware, it could be a heatsink that will live through some upgrades and CPU switches.

Thanks again to The Heatsink Factory for sending this our way – the 947-U is available at The Heatsink Factory.

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

Email Joe