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Old August 28, 2012, 03:51 PM
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Galcobar Galcobar is offline
Join Date: Dec 2009
Location: Richmond, B.C.
Posts: 430

My System Specs


Since PCP&C now sells modular supplies with 120 mm or larger fans, I doubt it. Then again, it was such a piece of FUD that it was really not worth paying attention to in the first place. It claimed PCP&C used 80 mm fans because it left room for larger and more robust components than did a 120 mm fan. Not mentioned was they were producing power supplies with the same components (Seasonic as OEM) as used in PSUs with 120 mm fans.
Most low-noise ATX power supplies today utilize a top-mounted 120mm fan rather than a rear-mounted 80mm fan. The 120's favorable reputation is based on the fact that under low to medium load conditions, the 120mm fan provides sufficient cooling at low RPM and low RPM fans are generally very quiet.

However, problems occur with this design when the load exceeds 50%-60%. Because the 120mm fan consumes about 1.5" of vertical space inside the PSU, heat sinks, capacitors, and other components are about 30% smaller in height compared to a PSU with a rear-mounted fan. The smaller parts can handle less current, so the maximum power available with the 120mm design is limited. And, because the heat sinks have less surface area, more air flow is needed with this design to keep the thermal situation under control. With 80%-100% load, the 120's fan speed can double and the noise level can jump by up to 20dB.

In conclusion, for systems that require more than 50% of the power supply's capacity, a well-engineered PSU with a rear-mounted 80mm fan will provide superior performance and reliability (due to larger components) at a noise level comparable to a PSU equipped with a 120mm fan.
I recall the discussion of the "myths" page on the PCP&C site being removed in early 2010 when they introduced the revamped Silencer series with 135 mm fans, ironically coinciding with Seasonic no longer producing the Silencer line.
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