AOpen XC Cube EX915: 775-socket SFF barebones

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It was a bit of a surprise to see a socket 478 heatsink retention frame around the 775 CPU socket. But it makes sense: For an integrated barebones system, the manufacturer can customize as necessary to make things work, without worrying about universal case form factors.

Socket 478 heatsink retention frame around the 775 CPU socket.

A geek's idea of good marketing? HS on the SB chip is an AOpen logo.

A close look at the center of the CPU socket shows the same type of thin-film temperature sensor found also in the EZ65. This sensor is used for the thermal feedback loop of the AOpen SilentBIOS fan control system.

The supplied integrated heatsink / fan is all copper, and incorporates both heatpipes and a duct or shroud. A 70 x 15mm fan is used . The base is flat and smooth, though slight machining marks can be felt. The steel spring clips are standard socket 478 fare: Pretty easy to use and quite secure. As in the EZ65, the fan is set up so that it blows across and through the fins horizontally.

Ends of the two heatpipes visible at the top.

Base is smooth enough.

Fan blades visible on other side through spacing in the fins, along with the heatpipes.

The HSF is installed with the fan on the left side of the case blowing towards the right. Some benefits from this side-to-side airflow arrangement:

  • Low back pressure to the fan compared to the conventional blow-from-top setup. This reduces turbulence noise.
  • Hot air from the CPU/HS is directed out of the case through the right side vent instead of using another fan to do that job.

These thermal airflow simulations for the EZ65 are still relevant here.

Outside air is drawn in through the large openings on the left near the front.
It flows across the drives, providing cooling, before being pulled into the PSU and the CPU cooler.

The CPU fan blows the air through the heatsink fins and directly out the right side vent on the other side.

The power supply is NOT a standard ATX design. It's smaller in every way, maybe a little bigger than 1/3 the size of standard ATX PSU. It uses an 80x20mm fan whose speed is thermally controlled. This is better than the smaller fans often used in SFF systems, because 80mm is about the smallest diameter fan that can push a decent volume of air without having to spin too fast. A label on the PSU provides the following specs:

AC Input
115 / 230 VAC, 50-60 Hz
DC Output
Current (A)
Max Power
Total Power

Surprisingly, it offers dual 12V lines! Note that the current for the individual voltage lines have almost no bearing on the total output power. For example, the max output for the individual +5V and +3.3 lines (56.1W and 90W), far exceed the max power available for the combination of the two lines. The PSU is equipped with passive power factor correction.

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