Case Fan Problem

Jun 6, 2018
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I recently built my PC a couple months ago and I have one reoccurring problem. My case fans (rosewill cullinan) won't turn on probably 1 out of every 10 times that I turn on my computer. The fans have LEDs when they are on their high setting, so I have it always on high, (at least for start up) that way I notice right away whether or not my fans are working or not. The LEDs will not turn on when this problem occurs. The solution I have found has been to shut down my computer, wait a few minutes, then turn it on again, however this may take a few tries. I regularly shut down my computer Monday-Thursday and leave it on sleep mode during the weekend. Does anyone have any idea what may be causing this problem?
 

Karadjgne

Titan
Herald
Ok. That hub is not much more than a case controlled hub. It's powered by a molex cable (came with the case) and it's that which powers any fans connected to it via the controller. Being 3pin, the fans are analog, so the rpm/led brightness will respond to the set speeds. None of the fans should be in any way associated with the motherboard. The cpu_fan header alone is the only fan header that needs to be populated.

So. I believe that's where the issue is, either with the molex power from the psu, the hub itself, or possibly its in the switch.

Have a multimeter handy. Next time the fans fail, unplug the molex, see if there's 12v. If there is, plug the molex back in, and wiggle the switch from H to L a few times.

It's not the fans themselves, it's something to do with the power delivery, possibly even as far back as a failure of the psu to supply the chain.
 
Jun 6, 2018
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Well, I did just that. Cables looked alright. It started up right away, I will return with results after a week or so. Hopefully that was the solution.
 
Here's what I think might be happening. You may have one fan that is pulling the voltage down on occasion. This causes the other fans not to start.

How many case fans do you have?

How are they connected to the MB? or however you have them connected?

 
Jun 6, 2018
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I have four case fans. Three in the front and one in the back. They are connected to a fan controller hub on cable management side of the case. I can provide a picture if needed.
 

Karadjgne

Titan
Herald
Some specific info would be helpful here. What case, what motherboard, is the hub a case included factory hub or is it aftermarket? Are the led fans factory originals or replacements, what fans exactly.

Sorry, but there's multiple possibilities, none of which I can see any of the fans being an issue, but more likely it's either a motherboard issue or possibly a fan setup issue.

Yes, a good closeup of the hub, with current fan setup, would be/could be helpful.
 
Jun 6, 2018
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The case is the Rosewill CULLINAN-RED ATX Mid Tower Gaming Case
The motherboard is the MSI Z270 GAMING PLUS LGA 1151 Intel Z270

The hub and fans are both factory original. The fans are all 120 mm LED and connected to the hub. Three front fans and one rear and all of them came pre-installed, however I had to plug their cables into the hub. I'll post some pictures hopefully tomorrow, but I might be busy then post Sunday
 

Karadjgne

Titan
Herald
Ok. That hub is not much more than a case controlled hub. It's powered by a molex cable (came with the case) and it's that which powers any fans connected to it via the controller. Being 3pin, the fans are analog, so the rpm/led brightness will respond to the set speeds. None of the fans should be in any way associated with the motherboard. The cpu_fan header alone is the only fan header that needs to be populated.

So. I believe that's where the issue is, either with the molex power from the psu, the hub itself, or possibly its in the switch.

Have a multimeter handy. Next time the fans fail, unplug the molex, see if there's 12v. If there is, plug the molex back in, and wiggle the switch from H to L a few times.

It's not the fans themselves, it's something to do with the power delivery, possibly even as far back as a failure of the psu to supply the chain.
 
Jun 6, 2018
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Alright, as soon as I can get my hands on a multimeter I will give it a shot. Thank You!
 

Karadjgne

Titan
Herald
It's possible that one fan is shorted out, backfeeding to the hub and making all the fans on the hub bunk, but that would likely also trip the protective circuitry in the psu if it detected a short on the 12v rail, causing a failure to boot.
 

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