IEI ACE-R150 fan replacement

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Some time ago I got an old QNAP NAS that uses two ACE-R150 power supplies in a redundant connection.

They where noisy from the start and they got worse as they drew in extra dust from the CNC machine, to the point where I could no longer work with the NAS powered on.

The fan is a very tight fit to the case – there are cut-outs on the top and bottom and it’s flush with the rest of the PSU.

On the back there is a blade style connector that includes the 220VAC part. There’s quite a lot of clearance, so it looks safe. Just for good measure, I cleaned it with fresh IPA before inserting the PSU back in the case.


The inside construction is very tight, with multiple modules mounted at 90 degrees. Everything is stuck down with some grey silicone, so there’s no chance things can move and touch to the primary side.

All the secondary heat-sinks are thermally coupled to the case, and also provide the top plate’s mounting points.


There where quite a lot of screws to undo. The fan is a SUNON one, with part number KDE1204PKV.

The noise was generated by worn bearings – nothing that I could fix, but still usable for some quick and dirty tests.


The replacement fan is a 12V Noctua NF-A4x20. The airflow is a little lower than the original one, but they’re almost inaudible.


The original fan was removed with it’s original connector and I did not have a proper one at hand. I chose to cut the new fan’s connector and crimp individual pins on the proper wires. They where isolated with thin heat-shrink tube. I chose to keep the entire cable of the new fan.


And finally fresh thermal paste is added, and everything is put back together. The wires from the new fan are kept in place by the pressure of the  top metal plate. Maybe a drop of hot-melt glue will add extra strength – next time I’ll remove them from the case.

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