fan to both header and psu cause issue?

[pcpete]

We have a client bring in what appears to be a bad motherboard. He had the fan both plugged into the mobo header and the psu. I don't think that would cause a problem as that would just be connecting a second ground and the same 12 volt rail to the 12 volt rail. Does that seem correct?

 

[frase]

Is this a AIO CPU Cooler - or just an air cooler? I don't think it really would matter, what is the mobo doing exactly - like DOA?
Have you tried taking the MOBO out of the case, remove CMOS Pin and reset (or take out battery) and RAM. Wait a few minutes - then replace and try again.

Try to power on pc using a flathead screwdriver on the POWER pins - incase of a bad Power Button (remote chance).

 

[pcpete]

We have done all the basics, it is dead. Just more curious if plugging both in could cause an issue I did not think so but wanted confirmation

 

[frase]

Oh ok np, Just check the boards mosfets, capacitors etc for any burn out or bulges. I normally do even if I replace the board, I'm just curious like that.

 

[NJW]

I don't think that would cause a problem as that would just be connecting a second ground and the same 12 volt rail to the 12 volt rail. Does that seem correct?

Not necessarily, unless it's a two-wire fan, which I doubt. Even so, there is more than one 12 V supply on a motherboard and if it's a PWM controlled fan, probably also with a tacho feedback, things get more complicated quite quickly. At least one of those fan headers is likely to have a direct connection to the SIO chip, which may well not be protected against unintended connections (viz. Lenovo laptops and charger sense pin).

 

[nlinecomputers]

Depends on how he plugged it up. If he plugged up to an LED output for his fan's voltage input and then plugged up the fan's ground to yet another LED output he could have had voltage trying to go both ways on the fan and the mobo. Could at least cook the fan,(have you tried with another fan?) or blown the board.

 

[frase]

Depends on how he plugged it up. If he plugged up to an LED output for his fan's voltage input and then plugged up the fan's ground to yet another LED output he could have had voltage trying to go both ways on the fan and the mobo. Could at least cook the fan,(have you tried with another fan?) or blown the board.

I have seen that before and someone did exactly that. Took a while to figure it out as client didn't tell me.

 

[NJW]

... as client didn't tell me.

Surely not.