The Apack Zerotherm CF800 heatsink is a compact aluminum finned socket 775 cooler. It has been designed to operate quietly, with the ability to scale the speed of its translucent fan automatically and tackle heat loads as high as 130W. That makes this 357 gram lightweight heatsink an ideal candidate for socket 775 Intel Pentium D/Core 2 Duo processors. The CF800 heatsink has a thermally responsive fan that adjusts its speed between 800-2300RPM, blowing upwards of 42CFM over over 2300mm2 of cooling surface area.

The units' four nickel plated copper heatpipes connect the copper base plate to the aluminum heat exchanger above. The Zerotherm CF800 is generally quiet under power, and performs fairly compared to the stock Intel Pentium D heatsink.

The heatsink installs with a set of spring tensioned screws onto a supplied metal back plate, so the motherboard will need to be removed prior to its use. The Apack Zerotherm CF800 ships with a pre-applied patch of Shin-etsu thermal compound, and comes with a small tube of extra thermal compound for any subsequent installation.

Apack Zerotherm CF800 Heatsink
	heatsink specsheet manufacturer: apack model no.: zerotherm cf800 materials: aluminum fins, nickel plated copper heat pipes, copper base fan mfg: protechnic mgt9212hs-s25 fan spec: 800-2300rpm, 12v, 0.25a fan dim: 25x95x95mm heatsink & fan dim: 79x106x95mm weight: 357 grams includes: pre-applied thermal compound Compatible with Sockets: LGA775 Est. Pricing: $38USD ($44CDN)

The Zerotherm CF800's Protechnic MGT9212HS-S25 fan has a thermistor attached to a short length of wire coming out of the motor hub, and this plays a crucial role in how the heatsink performs. The thermistor is cleverly located inside a well formed within in the array of aluminum fins, so it can accurately respond to the temperature of the metal, not the internal case air temperature. This enables the CF800 to scale the speed of the impeller as necessary, and cuts down on unnecessary noise.

At its slowest speed (800RPM), the 95mm diameter Protechnic fan barely produces 35 dBA noise. At its full speed of 2300RPM, the fan rumbles away with a moderately audible 48 dBA. A 3-pin power connector means this heatsink is not PWM compatible, but that doesn't really matter. The thermistor placement does a good job of allowing the fan to respond to the temperature load at any given moment.

A set of four copper heatpipes connect the aluminum fins to the base of the heatsink, which is made up of a large die cast aluminum mounting frame and a small 32x32mm small copper plate that makes direct contact with the processor IHS for optimal heat transfer.

The only really curious aspect about this heatsink is that the aluminum fins aren't nickel plated, and thus the heatpipe-to-aluminum fin joints are not soldered. If the joints are too loose thermal transmission may suffer.

Another bit which has us scratching our heads slightly is the die cast aluminum mounting base. It's big for starters. It's also directly attached to the nickel plated copper heatpipes and copper base, and yet it's completely flat on the opposite side for some reason. Given that this aluminum component is absorbing as much heat at the processor is putting out, it's hard to understand why Apack chose not to integrate some sort of low profile cooling fins on the rear of it. The large aluminum die cast mounting plate sits directly under the aluminum cooling fins, so it gets a full blast of air already... some cooling ridges would have only enhanced the heatsinks' thermal performance.

The Apack Zerotherm CF800 heatsink will be tested on FrostyTech's Intel LGA775 version of the Mk.II synthetic thermal temperature test platform, and compared against several reference LGA775 heatsinks. The whole test methodology is outlined in detail here if you care to know what equipment is used, and the parameters under which the tests are conducted. Now let's move forward and take a closer look at this heatsink, its acoustic characteristics, and of course it performance in the thermal tests!