How To Connect Case Fans To A Power Supply?


Connecting a case fan to a power supply is no rocket science. You need to know the right things to give it a shot. 

Here is a concise guide to connecting case fans to a power supply. Here we are connecting case fans to a CPU case. 

Things you need

  • Case fans
  • Case fan power supply 
  • Fan connectors (4 pin Molex connectors)
  • 3 pin Molex adapters 

Steps to follow

Step 1: Have the right case fan, connectors, and adapter

Your Molex connector and Molex adapter may or may not come with your case fan. In general, any fan connector has two sides, a 4 pin/Molex connector (male side) and 3-pin (female side). 

If your case fan power supply unit (PSU) does not have a 4 pin Molex connector, you may have to purchase it. Like Corsair PSU does not come with 4 pin Molex connector. 

Step 2: Find the right spot for the case fan

Where are you looking to install your case fan? Install it near the place where the heat radiated is maximum. You can install it on the rear side of the case, on the bottom side facing upward, on the top or/and on the sides. It depends on the number of case fans you are using. 

Step 3: Facing the fan

The face of the fan should be in the right direction. For instance, if you are installing it on the rear of the case, the front side of the fan should face the inside of the case. The rear part should face the CPU case. When installing at the bottom, the fan face should face up. 

Step 4: Connect the fan to the case

Place your fan in the desired spot and screw holes on all four sides of the fan casing. Use the screwdriver to tighten the screws. 

Step 5: Connect it to the PSU

To connect the case fan to the power supply unit, first, use your 4 pin Molex connector and connect it to your PSU. 

You need two cables here. A 4 pin Molex connector’s one side is attached to PSU. Similarly, 3 pin adapter’s 3 pin end (female) is attached to the case fan. Now, use the 4 pin side of the adapter and connect it to the 4 pin Molex connector i.e. to the PSU. 

The chain goes like Case fan – 3 pin adapter – (3 pin adapter’s other side connected to PSU’s 4 pin connector) – another side of 4 pin Molex connector – PSU. 

You can also connect your case fand directly to your motherboard. This is usually necessary if you are installing more than two case fans within the case. For gaming users, it is better to connect the case fans to the motherboard due to their intensive use. More usage means more heat being transmitted, thereby requiring more case fans. A PSU will be inefficient as it takes its own space and connects only one case fan at a time. This leads to a lack of space. 

If you are a user with moderate use, connecting a case fan to a power supply unit (PSU) is feasible. 

How do I connect 3 pin case fans to PSU?

Fan controllers usually come with 4 to 5 3-pin adapters to which you connect your fans to. Then you connect the controller to your PSU using a Molex adapter(in most cases) this saves you having to use multiple Molex adapters and keeps your wiring clean.

How do you install a case fan?

How to Install Case Fans into a Desktop PC

Can I plug the case fan into the CPU fan?

Theoretically yes. Since they all have either 3 or 4 pins you should be fine.

Do case fans plug into the power supply?

Yes. Those fans are either/or. You can use either the 3-pin motherboard connector or the 4-pin Molex direct from the power supply.

Are fans powered by the motherboard?

The CPU fans are controlled by the motherboard.

How do I connect RGB fans to PSU?

You will find one with a 6-pin connector on one end marked “Perif”, and that plugs into the corresponding socket of the PSU. That cable has THREE female 4-pin Molex output connectors on it, and you should plug one of those into the power input connector of the fan controller in your case.

Do RGB fans have 2 cables?

Every single RGB fan comes with at least 2 cables. The first cable which is used for the Motor of the fan is a “female” connector with either 3 or 4 holes in it. The second cable is used for the RGB, it’s much wider and ends on a 4-pin or 3-pin connector.

Will a 3-pin RGB connector work with 4-pins?

Yes, that will work, but not as you expect. The fundamental issue is that you can NOT power and control a 3-pin ARGB lighting system from a 4-pin plain RGB lighting header and there is NO simple adapter.

Can you use a 3-pin fan on a 2-pin connector?

The 3 Pin fan will fit onto the 2-pin you just need to match the holes and the pins and see which two contacts make the fan function.

Andy Avery

I really enjoy helping people with their tech problems to make life easier, ​and that’s what I’ve been doing professionally for the past decade.

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