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I'm hoping to power a couple 8 port netgear switches from an ATX style PSU. The netgear switches require 12v 1amp DC power. I'm hoping to create a few cables which convert the 2.5mm coaxial power connector from the netgear switch to a molex style connector for the PSU's 12v power. In theory, this sounds relatively easy but I want to be sure I don't need some type of protection for the switches, such as a fuse. Reading about the netgear power adapters it sounds like they have over voltage protection and short circuit protection. Is this something I need to worry about?

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Let's look at the general case, where you want to apply any kind of power to any kind of device, and the answer, intuitively, is yes, you want to have protection.

Overvoltage protection is installed so that, in the event of a failure, if the AC side decides to come visit the DC side, nobody gets hurt, and hopefully nothing else down the line gets destroyed. Short circuits can leverage a massive flow of current, leading to various faults up to and including fires - so we use fuses, PTC resistors, current limiters and various other tricks to prevent adventurous persons with paperclips from losing their eyebrows.

The good news is that if you are using a ATX power supply that meets or exceeds the actual specifications for a typical ATX power supply, and hasn't particularly been modified, you almost certainly already have most of the protection you would reasonably need to power said switch.

Now, I don't know that I would personally sacrifice all the space an ATX PSU takes up to do this kind of thing for two switches, but I get the feeling you might just be trying to make it work with what you have. In any case, as long as you remember to unplug the thing while you're working on it, this should work just fine, so long as the 12 volt rail can actually support all the load you're adding to it. Without posting numbers, you're the only person who can gauge that.

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  • \$\begingroup\$ Thanks for the prompt response :), much appreciated. I'm glad that it sounds like the protection won't be an issue since I'll be using the PSU. To give you some insight into what I'm working on, I'm converting my old gaming rig into a raspberry pi cluster. The PSU output specs are +3.3V 30A | +5V 29A | +12V1 16A | +12V2 18A | -5V 0.3A | -12V 0.8A | +5VSB 2.0A. I'm looking to run 20 or so PIs on the 5v rail of the PSU. I have a couple 8 port netgear switches that will mount nicely in the case so i figure to keep the wiring simpler I would mount them in the case and power them via the PSU. \$\endgroup\$
    – wildfan99
    May 4 '15 at 4:51
  • \$\begingroup\$ Cool stuff. You should be fine; you could benefit from a fuse inline to each switch, since the ATX PSU has enough supply to eat them for lunch in the event of a short. But the supply itself would prevent loss of eyebrows and apartments. \$\endgroup\$
    – Sean Boddy
    May 4 '15 at 4:54

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