Question Fan header and Molex

Apr 20, 2019
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Hello, my friend just got some new case fans that have 3 pin fan header and molex connections on each fan. He's hooked up each fan using all the connections. The 4 fans are connected to a single "fan hub" that is plugged into 1 fan header on the mobo, and also plugged into the Molex connections fron the PSU. He's not worried about speed control so I told him to just use the molex and not use the mobo fan header. Sorry for rambling, but i just wanted a little info.

1. Can anything be damaged by him leaving it this way?

2. what is the maximum number of fans that could be hooked up to a single mobo fan header?

Thanks for any info.
 
Do NOT connect both molex and 3-pin. That will pull too much power and melt the wiring and damage the fan and/or other parts.

2 fans per fan header is what I recommend, but you could probably get away with 3. But if you have a fan hub with extra power (via molex or SATA) you can use many fans. The Phanteks fan hub is powered by a single SATA cable and can connect up to 12 fans.
 
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Apr 20, 2019
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Well, it seems he didn't wait and tried to turn it on last night and it powered up for about 10 seconds and then shut down. Now the motherboard led lights up, but nothing will turn on. No beeps, no fans, just a solid led. He tried jumping the powet button pins but it wouldn't power up. He also tried testing the psu with a paper clip and it wouldn't power up, but when reconnected the led still lights up and is a solid light, no blinking.
 
Yes, you NEVER connect both the fan connector and the Molex connector. BUT, with all the fiddling around your friend has done since the failure, did he ever actually DISconnect the Molex connections from the PSU? If he still has BOTH connections done up, then of course it still will NOT work and could do damage!

So, start by disconnecting from the PSU Molex and use only the fan hub and its connection to the mobo fan header. See if that works.
 

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