SUMMARY: Although not for general P4 use, a good heatpipe CPU cooler.

A friend (Brett) dropped by for a chat and brought over Shuttle's PH4 Heat-Pipe. This is designed for use in Shuttle's small form factor systems (Model #s SS50C, SS51G, SV51F and SB51G), and as such is NOT necessarily suitable for general P4 use. Two factors limit its use:

• The heatpipe fin assembly overhangs the motherboard by quite a bit (3" - 4")

• The fan assembly is designed for mounting in Shuttle's case; mounting it to the radiator requires a user mod.

I should also note that the fan wire is very short - you might need to lengthen it. Shuttle is selling these for $39.

The fan assembly slips over the fins:

The four knurled screws are to mount the fan to Shuttle's chassis - to adapt it, you would need to design a different method; it should not be too difficult.

The fan is an Sunon Model #KD1208PTB1 - an 80 x 25mm unit rated at 39.5 cfm @ 3000 rpm, 33 dBA¹. I found it to be tolerably quiet - I measured its noise at 61 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 (2.3 watts).

The base is a copper baseplate:

Affixed to it is an aluminum finned top piece. I'm sure it adds to the cooling - good airflow over these fins may increase performance a bit. The heatpipes have a liberal application of thermal grease to enhance heat transfer.

The clip is a good one:

It's easy to mount and very secure.

Overall, the build quality is a step above other heatpipes I have seen and has a very sharp appearance.

I tested the Shuttle P4H on an Acorp 4S845A motherboard with a modified P4 1500 to read CPU case temps.

Motherboard	CPU Case Temp	Ambient Temp	Delta	C/W	MBM Temp
Acorp 4S845A	35.7 C	22.2 C	13.5	0.23	31 C¹

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 Shuttle P4H in the mid rank of heatsinks (Heatsink Ranking) tested to date.

This is the best performing heatpipe I've tested to date. I'm sure if you were to use a higher cfm fan, performance would improve, but at the expense of noise. As it is, it could be a very interesting conversation piece and decent for CPU cooling.

Thanks again to Brett for bringing this over to test out.

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

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