Akasa AK-965 socket 775 tower cooler

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Stock Intel push-pins are not our favorite mounting mechanism. But on the Akasa AK-965, they aren't inappropriate; at least the heatsink isn't much heavier than the stock Intel heatsinks. The push-pins on the AK-965 are not hard to use, as there is enough clearance for your thumb to get squarely atop each pin for maximum pressure if the fan is removed before you try to install the heatsink — either just the fan or the whole fan assembly. The installation probably can be done with the motherboard already installed in a case, but it's not wise. As with most large heatsink, it'll be easier to install the AK-965 with the board outside the case, and you'll have the chance to examine the underside of the board to make sure the pins are really secure.

The amount of tension applied with push-pins depends mostly on the distance between the base and the ends of the mounting frame where the pins are, and the stiffness of the mounting frame. In the Akasa AK-965, the distance seems slightly greater than normal, and the stiffness of the frame is very high. The last pin was quite an effort to insert. There is supposed to be a small degree of bowing of the motherboard when the heatsink is installed, but the amount of bowing with the AK-965 seems a bit excessive.

The pressure applied by the clip seems a bit high, judging from the amount of motherboard bending.

Installed and running on our open test bench motherboard.


Testing of heatsinks is normally done in accordance with our unique heatsink testing methodology, and one of our reference fans, but because the Akasa-965 comes with its own integrated fan, an unusual one in that it's a 92mm fan in an 80mm frame, we chose to test it with it own fan.

Key Components in Heatsink Test Platform:

  • Intel Pentium D 950 Presler core. TDP of 130W; under our test load, it measures 78W including efficiency losses in the VRMs.
  • ASUS P5LD2-VM motherboard. A basic microATX board with integrated graphics and plenty of room around the CPU socket.
  • Samsung MP0402H 40GB 2.5" notebook drive
  • 1 GB stick of Corsair XMS2 DDR2 memory.
  • FSP Zen 300W fanless power supply.
  • Arctic Silver Lumière: Special fast-curing thermal interface material, designed specifically for test labs.

Test Tools

  • Seasonic Power Angel for measuring AC power at the wall to ensure that the heat output remains consistent.
  • Custom-built, four-channel variable DC power supply, used to regulate the fan speed during the test.
  • Bruel & Kjaer (B&K) model 2203 Sound Level Meter. Used to accurately measure noise down to 20 dBA and below.
  • Various other tools for testing fans, as documented in our standard fan testing methodology.

Software Tools

  • SpeedFan 4.31, used to monitor the on-chip thermal sensor. This sensor is not calibrated, so results are not universally applicable; however,
  • CPUBurn, used to stress the CPU heavily, generating more heat than most real applications. Two instances are used to ensure that both cores are stressed.
  • Throttlewatch 2.01, used to monitor the throttling feature of the CPU to determine when overheating occurs.

Noise measurements were made with the fan powered from the lab variable DC power supply while the rest of the system was off to ensure that system noise did not skew the measurements.

Load testing was accomplished using CPUBurn to stress the processor, and the graph function in SpeedFan was used to make sure that the load temperature was stable for at least ten minutes. The stock fan was tested at four voltages: 5V, 7V, 9V, and 12V, representing a full cross-section of the its airflow and noise performance.

The ambient conditions during testing were 17 dBA and 21°C.


Stock Akasa Fan

The stock fan was tested for acoustics. We didn't do a full range of airflow / noise tests, but SPL and RPM measurements were taken at various voltages. At 12V, it's far too noisy our standards. The turbulence noise completely dominates. At 9V, it's better, but still too noisy. At 7V, it's not bad; the overall level is low enough that many users would find it quiet enough. The acoustic character is a combination of buzzing and hissing, which combine to impart an impression of people whispering some distance away. It is audible from a meter away, but inside a case, with other noise sources, it may simply blend into the overall noise. Interestingly, the fan refused to either start or run at 5V. The minimum voltage needed for consistent start was 5.5V.

Akasa AK-965 Fan Measurements
2700 RPM
1750 RPM
1170 RPM
670 RPM

Cooling Results

The performance achieved with the stock fan is excellent, the numbers posted at 12V and 9V being comparable to many of the top reviewed coolers. The caveat here, is the noise level, of course: The cooling performance is achieved at the cost of much higher noise than the best heatsink/fans. The performance of both acoustics and cooling are decent at 7V, which is probably the sweet spot (on this HSF) for silent PC users. The 37°C seen with the fan at 5.5V would end up with the CPU in >60°C range inside a real system, which is too high.

Akasa AK-965 w/ stock fan
Fan Voltage
°C Rise

What about changing the fan for a quieter one? It's feasible, but you have to go to an 80mm fan, which is a bit of a step down in that the volume of air moved for a given rotation speed is bound to go down. Remember, the stock fan has 92mm diameter blades in an 80mm frame. We gave it a go with our Nexust 80mm reference fan, which spins quite slowly and doesn't move much air, but is very quiet.

Stock fan removed, 80mm reference fan installed: Note the gaps around the edges of the fan mounting frame.

Akasa AK-965 w/ reference Nexus 80 fan
Load Temp: CPUBurn for ~20 mins.
°C Rise: Temperature rise above ambient (21°C) at load.
°C/W: based on heat dissipated by CPU (measured 78W); lower is better.

At all voltages, the Nexus fan is smoother and more pleasant to the ear. Naturally, cooling suffered, but at both 12V and 9V, it wasn't bad at all. The noise with the Nexus at 9V was somewhat preferable to the stock fan at 7V, and identical cooling was achieved. Testing was not done at 5V, as cooling would have been inadequate. The motherboard's voltage regulators probably run hotter than with the stock 92mm fan, as the 80mm fan provides hardly any airflow in that area.

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