Wednesday, January 13, 2016

Power Supplies And All That

Lately I had noticed that the power supply exhaust fan on my desktop HP would make noises like a coffee grinder occasionally. So when it started to get really annoying I figured I'd order a power supply, swap it out and then repair the old one.

No surprises here. The fan in the original was pretty noisy even after a dose of 3 in 1 oil, so I ordered another fan, cost $5. It arrived and it was the same make and model as the one I removed.

A couple of observations are in order. To get a Liteon power supply like the box came with and which you see pictured above you will cost you about a hundred bucks. So I ordered a cheapie "Replace Power" power supply from an online vendor, cost $22.79 and it was a drop in installation. The part number is RP-MPS3-420W, and it replaces the Liteon PS-5301-08HA.

Comparing the outputs reveals some differences. I'll put the Liteon's ratings in parentheses. +3.3v 11a (+3.3v 18a), +5v 12a (+5v 25a) +12v1 8a (+12v 19a) +12v2 8a (none) -12v 0.3a (-12v 0.8a) and +5vsb 2a (+5vsb 2a).

In most areas the Liteon has better capacity to deliver current on its individual legs but is limited to 300w combined.

There are a couple points of interest. The Liteon is much heavier and I believe that it is because of the massive extruded aluminum heat sinks. It is also thermostatically controlled and thus the fan does not run continuously as it does in the Replace Power unit. This is a nice feature because the exhaust fan rarely runs and most of the time doesn't bother me. It also has a small LED that indicates when power's on and it slowly fades as power is bled off after shutdown. The Replace Power does not have this feature.

The Replace Power also does not throw off a lot of RF noise, either. My last cheapie power supply for the Dell desktop that this replaced made a whistling noise that meant when it was running I couldn't listen to AM radio anywhere in the house. It's as good as the original in that respect.

Although they're both rated at 300w, the Liteon power supply seems to be more robust, and I'll either reinstall it or save it for another desktop if one should come my way as seems likely.

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