The Akasa AK-975Cu is a compact little Intel socket 775 heatsink that stands no more than 77mm tall. It comes with a 70mm PWM fan that varies in speed from 1000-3500RPM, and a convenient patch of pre-applied thermal compound on its base. The cooler is based on a copper block with aluminum fins and a pair of copper heatpipes to help distribute the heat to stubby cooling fins. All joints are soldered to lower thermal resistance. Installation is a snap because the Akasa AK-975Cu uses Intel's standard push-to-lock retention clips.

The heatsink is compatible with socket 775 Intel Pentium D/4 and Core 2 Duo CPUs, specifically in a 2U rack mountable chassis environment. If you recall, servers and other rack mounted enclosures are packaged in boxes that conform to the 1U, 2U, 3U etc. sizes. Each Unit of space is equivalent to 1.75" (44mm).

Generally, rack mounted enclosures utilized forced air cooling, whereby air is drawn into the chassis at the front by a phalanx of fans, and exhausted out the rear. Since heatsinks cannot exhaust up in such closed enclosures, and given that the prevailing air currents are all moving front to rear, exhausting down towards the motherboard can be inefficient. Thus most heatsinks for 1U or 2U enclosures direct airflow tangentially over cooling fins, as opposed to the more common impingement orientation used with desktop computer thermal solutions.

Anyway, on with the review! The Akasa AK-975Cu is clearly a no frills workhorse heatsink, and it retail for in the region of $20USD ($22CDN). Quite affordable really.

Akasa AK-975Cu Heatsink
	heatsink specsheet manufacturer: akasa model no.: ak-975cu materials: nickel plated aluminum fins, copper heatpipes, copper base fan mfg: akasa dfc701512m fan spec: 1000-3500rpm, 12v, 0.21a fan dim: 15x70x70mm heatsink dim: 77x56x89mm weight: est. 350 grams includes: lga775 mounting hardware, pre-applied thermal compound Compatible with Sockets: LGA775 Est. Pricing: $20USD ($22CDN / £10GBP)

The Akasa AK-975Cu is a pretty simple design, but the heatsink does rely upon two heatpipes. We're often asked to explain what heatpipes do, and don't... Think of it this way, as heat energy from the Intel processor reaches the two heatpipes, they move it from one spot to another. That's all. Heatpipes don't actually "cool", they're just very efficient at moving heat from one location to another, where fins or other heat exchangers do the actual "cooling" work.

On the inside of the heatpipes a working fluid absorbs the latent heat from the processor, causing it to undergo a change of phase. In our daily lives, water boils at 100°C, but as pressure is decreased the temperature gradient required to make water convert to vapour also drops. This is the foundation of the principle used with heatpipes.

Anyway, the working fluid inside converts to vapour as the temperature of the evaporator (hot side) of heatpipe increases. The liquid vapour is drawn towards the cooler end of the heatpipe where it condenses. As the hot vapour cools back into a liquid, the heat energy it stored is transferred back to the metal, but this time it is the surrounding cooling fins of the heatsink.

The condensed vapour, now working fluid once again, is drawn back towards the hot evaporator end of the tube by capillary action along an internal wick structure. As the liquid reaches the hot end once more, the entire process repeats itself.

The Akasa AK-975Cu 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 test methodology is outlined in detail here if you'd like 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.

360° View - Akasa AK-975Cu Heatsink Information on Frostytech's test methodology is available here.
	The Heatsink Fan: The Akasa AK-975cu heatsink stands 77mm high. It's low profile makes it ideal for 2U server chassis. The 70mm PWM fan spins at 1000-3500RPM. The fan connects by a 4-pin PWM fan power cable, and is backwards compatible with 3-pin connectors if that's what's available.
	Heatsink Top: Akasa's AK-975cu heatsink is a very simple unit; just two 6mm diameter copper heat pipes soldered to forty or so nickel plated aluminum fins. The fins are a good 41mm deep, and the body no more than 67mm across. Intel's push-to-click through motherboard hole retention clips are used, allowing quick installation and removal.
	Heatsink Exposed: Machine screws hold the 70mm fan in place, flush with the edges of the vertical aluminum fins. The copper heat pipes rise up 47mm before threading their way through the fins of the heatsink. Each fin is 0.4mm thick and spaced 1.40mm apart. The heatpipes are recessed into the copper base slightly, which measures 6.4mm thick itself over the CPU.
	Heatsink Top: Here we can see how the heatpipes are positioned slightly off-center on the body of the heatsink. One heatpipe is tilted towards the front, while the other remains straight. Both copper heatpipes are soldered to the nickel plated aluminum fins and copper base. Furthermore, the aluminum fin assembly is soldered to the copper base of the Akasa AK-975Cu heatsink.
	Heatsink Side A: On the whole, the Akasa AK-975Cu is a very compact heatsink. It has to be to fit in the confined spaces of a 2U rack mountable chassis. Each heatpipe is recessed about 3mm into the copper base, but curiously they are set to the rear of the heatsink instead of being centered over the space where the Intel IHS makes direct contact.
	Heatsink Base: The base of the Akasa AK-975Cu measures 38x40mm in size and comes with a pre-applied patch of grey thermal compound. The copper has a light sanded surface finish and is flat in both axis. Surface roughness is on the order of ~48 microinches, which is considered good. The heatsink does not come with K8 mounting hardware, which by the looks it is an option.