Forgot to turn off psu whe taking cpu_fan 3 pin for aio pump in and out.

[Niklas1120]

Hey guys, i was just wondering. The other day i had to check the connection of my 3 pin aio pump, which is plugged into the cpu_fan header. Afterwards i realized i forgot to turn off the psu so there was still power in the board. Eveything appears to be working fine and im probably overthinking this, but do you think this could have caused any harm? Like i said all i unplugged and replugged during this time, was the 3 pin connector.

[DoctorNick]

No. Even if you disconnected when PC was on nothing would happen. 

[Niklas1120]

Awesome thank you man!

[Guest]

You can always hot-swap fans. Just make sure not to touch or accidentally short the connector.

[Niklas1120]

I mean i probably hit the pins with my finger haha

[mariushm]

The recommendation to turn off the power supply is so you won't get scared if there's a few sparks when you insert the connector and for extra extra safety.

 

The pump is a motor, similar to the ones in regular fans, only more powerful. Like any motor, it needs more power to start turning compared to the power it needs while it runs... this is because the motor has to figth forces like inertia, friction. Once the motor starts spinning and the axle is lubricated, the friction drops and the power amount drops and everything is right with the world.

 

So when you insert the connector into the header, the power supply sees a sudden power draw, similar to how a video card would switch from doing almost nothing in windows to suddenly playing a game, for less than a second .. picture a game just finishes loading and you see the first frames of a level... the video card suddenly demands a bit more power.

For modern power supplies, this is nothing, and they can easily handle this small burst of power.

You may see sparks on the header because until the connector is fully plugged in, it's not a perfect contact so it's like two wires rubbing against each other, and you could get sparks.

 

Pulling the connector out can cause problems in extremely rare cases, and with poorly designed products.

Any motor (inside a fan, inside a water pump) can work both ways .. you can give it energy to make it spin but if you suddenly stop giving it power, the fan or motor will keep spinning and for a short period of time, that spinning can generate electricity which can go back through the wires. 

Also, if the motor doesn't use permanent magnets, when that magnetic field generated inside the motor produced by electric magnets breaks down the voltage increases, it's like a spike, which can go back through the wires. 

So for example, you can power a computer fan with 12v and have it spin at 2000 rpm, and you turn off power ... for a brief period of time, you may see a voltage on the wires higher than 12v before it drops down to 0.

 

Most computer fans and motors have protections against this, there's components which block energy from going backwards, and most motherboards also have protections near the headers to block this. So it's very rare that anything bad would happen.

 

So it's a good practice to turn off your PC before you connect or disconnect fan headers and pumps, but you don't have to turn off the power supply or unplug the pc.

 

[Niklas1120]

21 minutes ago, mariushm said:

The recommendation to turn off the power supply is so you won't get scared if there's a few sparks when you insert the connector and for extra extra safety.

 

The pump is a motor, similar to the ones in regular fans, only more powerful. Like any motor, it needs more power to start turning compared to the power it needs while it runs... this is because the motor has to figth forces like inertia, friction. Once the motor starts spinning and the axle is lubricated, the friction drops and the power amount drops and everything is right with the world.

 

So when you insert the connector into the header, the power supply sees a sudden power draw, similar to how a video card would switch from doing almost nothing in windows to suddenly playing a game, for less than a second .. picture a game just finishes loading and you see the first frames of a level... the video card suddenly demands a bit more power.

For modern power supplies, this is nothing, and they can easily handle this small burst of power.

You may see sparks on the header because until the connector is fully plugged in, it's not a perfect contact so it's like two wires rubbing against each other, and you could get sparks.

 

Pulling the connector out can cause problems in extremely rare cases, and with poorly designed products.

Any motor (inside a fan, inside a water pump) can work both ways .. you can give it energy to make it spin but if you suddenly stop giving it power, the fan or motor will keep spinning and for a short period of time, that spinning can generate electricity which can go back through the wires. 

Also, if the motor doesn't use permanent magnets, when that magnetic field generated inside the motor produced by electric magnets breaks down the voltage increases, it's like a spike, which can go back through the wires. 

So for example, you can power a computer fan with 12v and have it spin at 2000 rpm, and you turn off power ... for a brief period of time, you may see a voltage on the wires higher than 12v before it drops down to 0.

 

Most computer fans and motors have protections against this, there's components which block energy from going backwards, and most motherboards also have protections near the headers to block this. So it's very rare that anything bad would happen.

 

So it's a good practice to turn off your PC before you connect or disconnect fan headers and pumps, but you don't have to turn off the power supply or unplug the pc.

 

Damn, thank you so much for the in depth response man. This helped ease my mind