• Case fan only runs at max speed.
    12 replies, posted
I've recently run into a strange problem with one of my case fans. If I set the voltage to anything lower than 100 percent with my fan controller the fan fails to spin but it still lights up and struggles to move but can only manage to sputter back and forth. I've already switched around the fan connections with the controller to no avail. Anyone ever seen an issue like this or know what the problem could be?
Are you sure the fan supports multiple speed modes? I've tried playing with variable speed on my fans before and a few of them did the same as yours. It could be your fan controller though.
Well, I have the same exact fan next to it and it is capable of running at slower speeds. It ultimately isn't that much of a big deal because I don't mind running it at 100% because it doesn't produce much noise but it doesn't allow me to run my fan controller on automatic because the controller will try to run it around 40-60 % most of the time.
I'm not knowledgeable with fans in computers, but I do believe they are controlled by PWM, not the voltage you supply it with. Then again, I have no idea what the inputs to the fan controllers actually change, it could indeed be the voltage output to the fan. Anyway, it sounds as though it's not getting enough power to spin correctly. Check for foreign objects on the fan. Maybe you have some hair tied up in there, adding friction to the bearing and slowing it down perhaps
Thanks for clearing that up Trumple. I'll have a look at it sometime tonight or tomorrow, I have already examined it for such an obstruction but it is definitely possible that I missed it.
My fan controller wont let me go beneath 50%, they just shut off. Probably something to do with the fans itself, not the controller.
Still having the same problem. Again I have the exact same fan model right next to it which is capable of going as low as 40% but the fan I'm dealing with will only complete a fan revolution at 100%. I've checked the fan for any impairments that could be blocking of movement and have seen nothing. Anyone with any other insights?
[QUOTE=Trumple;34232851]I'm not knowledgeable with fans in computers, but I do believe they are controlled by PWM, not the voltage you supply it with. Then again, I have no idea what the inputs to the fan controllers actually change, it could indeed be the voltage output to the fan.[/QUOTE] Wrong, not all computer fans are PWM controlled. There are three types of computer fans: 1) Fixed speed 2) Voltage controlled 3) PWM controlled Fixed speed fans are generally either powered by a molex connector or by the 3 pin fan header on the motherboard. They will only have two wires for the fan header (+12v and GND.) These types of fans are mostly found in PSUs and really cheap cases. Voltage controlled fans use the 3 pin fan header and use all three pins (VCC, GND and a sensor wire to detect fan RPM.) This type of fan is controlled by a thermistor that is either on the fan itself, or via the BIOS that has a temperature probe associated with the specific fan connector (usually one of the CPU zones.) Both methods vary the voltage sent to the fan based on heat. PWM fans use four wires and an extended 4 pin fan header (VCC, GND, Sense and PWM.) These fans are more expensive than the other types from added circutry on the fan. Intel reference CPU coolers have used PWM controlled fans since the LGA775 socket was introduced. [QUOTE=Strider*;34409096]Still having the same problem. Again I have the exact same fan model right next to it which is capable of going as low as 40% but the fan I'm dealing with will only complete a fan revolution at 100%. I've checked the fan for any impairments that could be blocking of movement and have seen nothing. Anyone with any other insights?[/QUOTE] Turn the computer off and spin both fans with your hand slowly. Check to see if the malfunctioning fan is more difficult to spin than the other fan. If it is, it likely mean the lubrication in the bearing has burned and turned into carbon dust, creating lots of friction the fan has to work against to spin.
[QUOTE=bohb;34411043]Turn the computer off and spin both fans with your hand slowly. Check to see if the malfunctioning fan is more difficult to spin than the other fan. If it is, it likely mean the lubrication in the bearing has burned and turned into carbon dust, creating lots of friction the fan has to work against to spin.[/QUOTE] From what I can tell that doesn't seem to be the issue, so no luck so far.
@bohb Some motherboards also can use PWM on 3 pins fans, but usually only with software such as speedfan. @Strider Have you tried moving the fan onto another chanel of the fan controller (assuming it is multi-channel). There could be a problem with one channel on the controller.
[QUOTE=rhx123;34548777] Have you tried moving the fan onto another chanel of the fan controller (assuming it is multi-channel). There could be a problem with one channel on the controller.[/QUOTE] Yeah I did switch channels on the controller to no avail. Another quick question I have is if it is better to constantly run a fan at higher speeds or lower speeds because I have heard different things from multiple people. I'd be a lot more comfortable with this problem if the only issue it could cause is the noise from the higher fan speeds and not damage on the fan.
[QUOTE=rhx123;34548777]@bohb Some motherboards also can use PWM on 3 pins fans, but usually only with software such as speedfan.[/QUOTE] That's controlling the fan by changing the voltage to the fan. You can't control a non-PWM fan with PWM since no circutry exists on the fan and there's no wire to send PWM information to the fan. [QUOTE=Strider*;34548890]Yeah I did switch channels on the controller to no avail. Another quick question I have is if it is better to constantly run a fan at higher speeds or lower speeds because I have heard different things from multiple people. I'd be a lot more comfortable with this problem if the only issue it could cause is the noise from the higher fan speeds and not damage on the fan.[/QUOTE] It depends on the type of fan. Some fans are designed in such a way that the airflow created by the fan also cools the internal motor and prevents it from overheating. Slowing those types of fans down will cause the fan to run hotter and have a shorter lifespan. PWM/Voltage controlled fans are designed to run at varying RPMs and shouldn't have this issue. The only other reason I could think the fan failed is that the controller IC on the fan burned. Most computer fans are brushless inductor fans and have a timing chip to make the fan work. If the controller burns, the fan won't work.
[QUOTE=bohb;34552544] The only other reason I could think the fan failed is that the controller IC on the fan burned. Most computer fans are brushless inductor fans and have a timing chip to make the fan work. If the controller burns, the fan won't work.[/QUOTE] Well the fan still runs from what I can tell flawlessly on 100% speed but nothing below that. From what you've said that I'm assuming it shouldn't be a problem to run it at 100% until I either fix the fan or replace it.
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