Corsair 750D case fans don't work

[NGX]

Hi,

I purchased a 750D a while ago, it was finally delivered today and i installed my components into it. I have all 3 case fans plugged in but they will not spin. If I have 1 plugged in, it will spin, if I have 2 plugged in, only 1 will spin and if I have 3 in then none will spin, why is this?

I don't think its the fans because when all 3 are plugged in and I turn on the system, they move for a second but then stop moving.

My systems specs are listed below:
CPU: FX 8320 @ 4.2 GHz
GPU: R9 280x Gigabyte Windforce Rev 2
PSU: Corsair VS650
MOBO: ASUS M5A97 R2.0

Any help would be greatly appreciated!
Thank you!

 

[techgeek]

Are your fans connected to the motherboard? Are they DC fans or PWM fans?

If you are trying to power all three fans from one header on the motherboard, that could be the problem. Most motherboard fan controllers can only supply at most 1A for each connector. So if you are using some sort of splitter cable to power all three off of one header the motherboard is detecting what it thinks as a short (or too great a load) and shutting off power to that header.

 

[Gingerbread]

I am assuming you have plugged the case fans in the motherboard Chassis fan headers

 

[NGX]

Are your fans connected to the motherboard? Are they DC fans or PWM fans?

If you are trying to power all three fans from one header on the motherboard, that could be the problem. Most motherboard fan controllers can only supply at most 1A for each connector. So if you are using some sort of splitter cable to power all three off of one header the motherboard is detecting what it thinks as a short (or too great a load) and shutting off power to that header.

All fans are plugged into their own header on the motherboard, the exhaust being plugged into "SYS_FAN1" and the 2 intakes being plugged into "CHA_FAN 2 & CHA_FAN 3" respectively. (SYS_FAN 1 counts as CHA 1 which is why I didnt say CHA 1) As for PWN or DC, no idea. All I know is they are the stock fans that came with the case.

 

[techgeek]

PWM fans will have a 4 socket header connector on them, DC fans will have a 3 socket header connector on them.

The reason this is important is if your case comes with PWM fans and your motherboard is set up to supply DC fans on those header connectors, then the fans will not spin. The other way round works though (but the motherboard can't control the fans, they'll run at 100% all the time) if the headers are set up to power PWM fans and you have DC fans plugged into them.

 

[NGX]

PWM fans will have a 4 socket header connector on them, DC fans will have a 3 socket header connector on them.

The reason this is important is if your case comes with PWM fans and your motherboard is set up to supply DC fans on those header connectors, then the fans will not spin. The other way round works though (but the motherboard can't control the fans, they'll run at 100% all the time) if the headers are set up to power PWM fans and you have DC fans plugged into them.

They are DC then, they are plugged into 4 socket headers on the motherboard but it allows 3 socket fans to be plugged in. I'm not sure how to change the BIOS to or whatever to make it run using DC.

 

[NGX]

I am assuming you have plugged the case fans in the motherboard Chassis fan headers

You would be correct in assuming that

 

[techgeek]

Having a look at your motherboard manual, I don't see any options in the BIOS to switch the fan mode from DC to PWM or vica versa. It looks like they all operate in strictly PWM mode. This should cause all your fans to operate at 100%.

Have a look at page 3-23 of you motherboard manual. There is an option for fan profile, just for sh1ts and giggles, try setting them to turbo for all the chassis fans.

 

[Gingerbread]

Fans should be auto spinning as soon as your PC boots fully, only reason not to spin would be insufficient power, which seems odd.

 

[techgeek]

Also make sure that you have the fan connectors covering the correct 3 pins on the header. Please don't flame me if you have it right, but the connectors can be forced to go on the wrong way. There is a notch on the back of the connector on the fan cable, this has to line up with the blade on the 4 pin connector on your motherboard.

The down side to all this is without PWM fans, your case fans are going to run at 100% all the time. Unless these are the quietest stock case fans ever created, once you get it working, you'll want to use headphones all the time.

 

[NGX]

Also make sure that you have the fan connectors covering the correct 3 pins on the header. Please don't flame me if you have it right, but the connectors can be forced to go on the wrong way. There is a notch on the back of the connector on the fan cable, this has to line up with the blade on the 4 pin connector on your motherboard.

The down side to all this is without PWM fans, your case fans are going to run at 100% all the time. Unless these are the quietest stock case fans ever created, once you get it working, you'll want to use headphones all the time.

I'm pretty sure they're plugged in right, the fans have notches on the top and the fan header on the motherboard also have them and it only allows me to plug it in one way, i notice with the lower intake fan, if I spin it with my hand, it starts to spin on its own and is currently doing it right now, however the other 2 don't do that. Do you think the motherboard can't supply enough power? Should I just get a fan header to molex adapter? I don't see this working for me anytime soon.

 

[techgeek]

Also make sure that you have the fan connectors covering the correct 3 pins on the header. Please don't flame me if you have it right, but the connectors can be forced to go on the wrong way. There is a notch on the back of the connector on the fan cable, this has to line up with the blade on the 4 pin connector on your motherboard.

The down side to all this is without PWM fans, your case fans are going to run at 100% all the time. Unless these are the quietest stock case fans ever created, once you get it working, you'll want to use headphones all the time.

I'm pretty sure they're plugged in right, the fans have notches on the top and the fan header on the motherboard also have them and it only allows me to plug it in one way, i notice with the lower intake fan, if I spin it with my hand, it starts to spin on its own and is currently doing it right now, however the other 2 don't do that. Do you think the motherboard can't supply enough power? Should I just get a fan header to molex adapter? I don't see this working for me anytime soon.

Did you go into the BIOS and set it to Turbo for your chassis fans?

 

[NGX]

Also make sure that you have the fan connectors covering the correct 3 pins on the header. Please don't flame me if you have it right, but the connectors can be forced to go on the wrong way. There is a notch on the back of the connector on the fan cable, this has to line up with the blade on the 4 pin connector on your motherboard.

The down side to all this is without PWM fans, your case fans are going to run at 100% all the time. Unless these are the quietest stock case fans ever created, once you get it working, you'll want to use headphones all the time.

I'm pretty sure they're plugged in right, the fans have notches on the top and the fan header on the motherboard also have them and it only allows me to plug it in one way, i notice with the lower intake fan, if I spin it with my hand, it starts to spin on its own and is currently doing it right now, however the other 2 don't do that. Do you think the motherboard can't supply enough power? Should I just get a fan header to molex adapter? I don't see this working for me anytime soon.

Did you go into the BIOS and set it to Turbo for your chassis fans?

I'll do that right now and message you back when i've done it.

 

[NGX]

Also make sure that you have the fan connectors covering the correct 3 pins on the header. Please don't flame me if you have it right, but the connectors can be forced to go on the wrong way. There is a notch on the back of the connector on the fan cable, this has to line up with the blade on the 4 pin connector on your motherboard.

The down side to all this is without PWM fans, your case fans are going to run at 100% all the time. Unless these are the quietest stock case fans ever created, once you get it working, you'll want to use headphones all the time.

I'm pretty sure they're plugged in right, the fans have notches on the top and the fan header on the motherboard also have them and it only allows me to plug it in one way, i notice with the lower intake fan, if I spin it with my hand, it starts to spin on its own and is currently doing it right now, however the other 2 don't do that. Do you think the motherboard can't supply enough power? Should I just get a fan header to molex adapter? I don't see this working for me anytime soon.

Did you go into the BIOS and set it to Turbo for your chassis fans?

Did nothing 🙁

 

[techgeek]

Here's another option, rather than Turbo, set it to Manual. This will expose more options, set the minimum and maximum duty cycle to 100%.

 

[NGX]

Here's another option, rather than Turbo, set it to Manual. This will expose more options, set the minimum and maximum duty cycle to 100%.

I have a weird issue, if I have any fan plugged into exhaust then no fans will turn on., This leads me to believe that there is insufficient power. Currently, with no exhaust fan plugged in, the two intakes are spinning. I might just buy a molex adapter for my exhaust fan and run off that. Thank you for your help.

 

[techgeek]

Have you tried the exhaust fan by itself? It's possible that the fan is faulty (shorted) and causing the power to be loaded down. Does that fan spin easily when you flick it with your finger?

From your description, I'm betting that fan is bad. If so, you could e-mail Corsair support, I bet they'd ship one out to you lickety split.

 

[RobCrezz]

It sounds like the fans are not getting enough voltage to get them started. Set them all the full speed (turn off PWM control for the chassis fans), save bios settings and turn off pc. Then turn back on again.

If they still dont work then get adaptors to just run them straight off the PSU.

 

[techgeek]

It sounds like the fans are not getting enough voltage to get them started. Set them all the full speed (turn off PWM control for the chassis fans), save bios settings and turn off pc. Then turn back on again.

If they still dont work then get adaptors to just run them straight off the PSU.

The motherboard doesn't have any options for setting them to PWM or DC.

If I've interpreted what he's said, the exhaust fan in that case stops any fan from turning.

@ the OP, have you tried the exhaust fan by itself or with just one of the other fans?