Fans not spinning

SM Phoo · May 20, 2020

Hey guys, sorry for the second question within 30mins, but this is the last!

Built PC for a friend, I've installed 3 Deepcool RF120 fans. As cable management isn't great using the fan block to plug them all in one place, I decided a neater look would be to plug them into the motherboard direct.

Back fan, plugged into Sys_fan1 works totally fine, but the other two, which I've put in fan_2 and fan_3 don't spin (They light up, but thats a separate cable)

What would be the best way to troubleshoot this.

Is there a way to see if the fans are recognised at all?

Thanks

Bombastinator · May 20, 2020

They spun before in the previous configuration? If so it’s likely not a problem with the fans themselves

A few things I can think of:

1: the fans aren’t plugged in correctly. Make sure they’re actually plugged into fan headers in the correct way

2: the motherboard fan power set up is messed up in some way.

there are a couple of points where fan control can be done from. The lowest level one is generally bios.
there are higher level app based ones too, so they would all need to be checked. Others may not be there though. Bios is always there though and if it has fan controls it’s the place to start. There you can turn power on and off to different headers as well as doing fan ramp control. Fan ramp control controls the speed of a fan according to the heat level of a particular sensor in the chip. These can be set as low as zero, so a fan may not be coming on because a particular part hasn’t gotten hot enough yet.

2a: because fan ramp is controlled by heat sensors if the heat sensor is broken the thing won’t work (this isn’t very likely. The sensors are tough)

2b: fan motors require a certain amount of voltage to get moving. If the fan control is set low they might be providing power, but not enough power to get over the initial hump of starting the fans to spin. If this is the case if you start the fan spinning with a finger the power will kick in and it will keep spinning.

SM Phoo · May 20, 2020

13 minutes ago, Bombastinator said:

They spun before in the previous configuration? If so it’s likely not a problem with the fans themselves

A few things I can think of:

1: the fans aren’t plugged in correctly. Make sure they’re actually plugged into fan headers in the correct way

2: the motherboard fan power set up is messed up in some way.

there are a couple of points where fan control can be done from. The lowest level one is generally bios. There you can turn power on and off to different headers as well as doing fan ramp control. Fan ramp control controls the speed of a fan according to the heat level of a particular sensor in the chip. These can be set as low as zero, so a fan may not be coming on because a particular part hasn’t gotten hot enough yet.

2a: because fan ramp is controlled by heat sensors if the heat sensor is broken the thing won’t work (this isn’t very likely. The sensors are tough)

2b: fan motors require a certain amount of voltage to get moving. If the fan control is set low they might be providing power, but not enough power to get over the initial hump of starting the fans to spin. If this is the case if you start the fan spinning with a finger the power will kick in and it will keep spinning.