Question Connecting an external power load to a running computer

Pimpom

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May 11, 2008
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If an extra moderate load is connected to the PSU of a computer while it is running - say a 1A load to the 12V rail via a Molex connector, is there a danger of corrupting or damaging something, especially an existing HDD? Connections like USB are obviously designed to avoid this by sequencing the contacts, and possibly by software negotiation.

What about an improvised load connector, such as a Molex to barrel DC connector? I'm concerned more about the effect on the internal components of the running computer rather on the external load.
 

lvt

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Apr 19, 2021
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To be clear, my concern is not about the magnitude of the load, but about possible spikes occurring while the connector is being inserted.
You said "moderate load" on the first post, a moderate load won't affect anything.

The only thing you might be worry for is the CPU, fortunately, according to ATX specs, the CPU gets a dedicated power cable that comes from separate 12V rail.

BTW, do you have to use the PSU's 12V to run your thing? If you are so concerned about it, you also can use a 12V adapter.
 

Pimpom

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This is for general reference, in case it's more convenient to use the computer's PSU for some future application. Most computer builds have plenty of extra current capability to spare.
 

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