How to connect a 4 pin molex fan to 4 pin motherboard header?

ultra23 · Aug 14, 2013

How do I connect a 4 pin molex fan to a 4 pin motherboard header. I have 4 fans with 4 pin molex ends and a motherboard with (4) 4 pin headers. What would I use to connect each of these fans to the motherboard? Are there adapters? What are my options?

burdenbound · Aug 14, 2013

You can hook the fans up with either the molex connection or the connection to the motherboard. They are there to give people the option in case their motherboard does not have the connections. If you go with the molex connections you will not be able to control the fan speeds from within the system.

burdenbound · Aug 14, 2013

If your fans only came with 4 pin molex connections and you want to control their speed you may want to look into a fan controller like this one http://www.newegg.com/Product/Product.aspx?Item=N82E16811992005

ultra23 · Aug 14, 2013

burdenbound :

I actually wanted to connect these directly to the motherboard headers so I can control the speed.

burdenbound · Aug 14, 2013

ultra23 :

I do not know if you can go from a 4 pin molex to 4 pin motherboard connection because the molex is strictly power where as the 4 pin motherboard is power plus connections for monitoring and control which molex lacks. Thats why you need a separate controller because it controls fan speed by fluctuating the power to the molex connection.

ultra23 · Aug 14, 2013

burdenbound :

ultra23 :

I do not know if you can go from a 4 pin molex to 4 pin motherboard connection because the molex is strictly power where as the 4 pin motherboard is power plus connections for monitoring and control which molex lacks. Thats why you need a separate controller because it controls fan speed by fluctuating the power to the molex connection.

If the molex is just strictly power wouldn't it have just 2 wires (a pos and a ground wire) instead of 4 wires?

burdenbound · Aug 14, 2013

molex pinout http://pcsupport.about.com/od/insidethepc/a/molex-pinout-4-pin-psu.htm

4 pin fan pinout http://www.allpinouts.org/index.php/Motherboard_(CPU)_4_Pin_Fan

burdenbound · Aug 14, 2013

You need to highlight and copy that second link, not sure why it didn't grab the whole thing.

photonboy · Aug 14, 2013

EXAMPLE PWM FAN (it's 92mm. You likely want 120mm. Again, just an example):
http://us.ncix.com/products/?sku=77369&vpn=NF-A9x14%20PWM&manufacture=Noctua&promoid=1071

More information:
Fan control checklist:

*There are two types of fans that have speed control. MOLEX is usually not controllable, though there are some rare exceptions which work with 3-pin/4-pin adapters. The two types are:
1) VOLTAGE (3-pin), and
2) PWM (4-pin)

Additionally the FAN controller must be capable of controlling this. My motherboard supports both PWM and Voltage for the case fans, but only PWM for the CPU_FAN controller. Older motherboards may have VOLTAGE only for everything.

1) Determine what TYPE of controller you have (not always obvious. May have to just try a fan).

2) Enable fan control in the BIOS if needed.

3) Download and install your motherboard fan control software (motherboard support site).

4) Play with the fan profile. Set to 100%, then 40% to see if the speed changes.

5) Example fan profile: case fan at 40% speed until 40degC then RAMP up to 100% speed at 80degC (it will never reach 100%).

If you don't own a fan you can find some fairly cheaply but you need to find out what controller you have. When you buy the fan make sure you can control the speed:

*Let's say you want to buy a PWM fan. It should show a RANGE, not one speed.

ultra23 · Aug 14, 2013

burdenbound :

If these fans are not compatible then I guess I will be buying new fans that are PWM compatible. Thanks!

ultra23 · Aug 14, 2013

photonboy :

EXAMPLE PWM FAN (it's 92mm. You likely want 120mm. Again, just an example):
http://us.ncix.com/products/?sku=77369&vpn=NF-A9x14%20PWM&manufacture=Noctua&promoid=1071

More information:
Fan control checklist:

*There are two types of fans that have speed control. MOLEX is usually not controllable, though there are some rare exceptions which work with 3-pin/4-pin adapters. The two types are:
1) VOLTAGE (3-pin), and
2) PWM (4-pin)

Additionally the FAN controller must be capable of controlling this. My motherboard supports both PWM and Voltage for the case fans, but only PWM for the CPU_FAN controller. Older motherboards may have VOLTAGE only for everything.

1) Determine what TYPE of controller you have (not always obvious. May have to just try a fan).

2) Enable fan control in the BIOS if needed.

3) Download and install your motherboard fan control software (motherboard support site).

4) Play with the fan profile. Set to 100%, then 40% to see if the speed changes.

5) Example fan profile: case fan at 40% speed until 40degC then RAMP up to 100% speed at 80degC (it will never reach 100%).

If you don't own a fan you can find some fairly cheaply but you need to find out what controller you have. When you buy the fan make sure you can control the speed:

*Let's say you want to buy a PWM fan. It should show a RANGE, not one speed.

Thank you photonboy. I will try this. I have a 990fx Sabertooth Motherboard. All are (6)4 pin headers for the fans except one and it is a 3 pin header.

ultra23 · Aug 14, 2013

photonboy :

EXAMPLE PWM FAN (it's 92mm. You likely want 120mm. Again, just an example):
http://us.ncix.com/products/?sku=77369&vpn=NF-A9x14%20PWM&manufacture=Noctua&promoid=1071

More information:
Fan control checklist:

*There are two types of fans that have speed control. MOLEX is usually not controllable, though there are some rare exceptions which work with 3-pin/4-pin adapters. The two types are:
1) VOLTAGE (3-pin), and
2) PWM (4-pin)

Additionally the FAN controller must be capable of controlling this. My motherboard supports both PWM and Voltage for the case fans, but only PWM for the CPU_FAN controller. Older motherboards may have VOLTAGE only for everything.

1) Determine what TYPE of controller you have (not always obvious. May have to just try a fan).

2) Enable fan control in the BIOS if needed.

3) Download and install your motherboard fan control software (motherboard support site).

4) Play with the fan profile. Set to 100%, then 40% to see if the speed changes.

5) Example fan profile: case fan at 40% speed until 40degC then RAMP up to 100% speed at 80degC (it will never reach 100%).

If you don't own a fan you can find some fairly cheaply but you need to find out what controller you have. When you buy the fan make sure you can control the speed:

*Let's say you want to buy a PWM fan. It should show a RANGE, not one speed.

These are actually the fans that I have

http://apevia.com/ProductsInfo.asp?KEY=CF12SL-UGN

It is strange it shows one speed but a voltage range.

ultra23 · Aug 14, 2013

burdenbound :

Thanks for this information. This probably why I could not find an adapter. I will go with other fans if these are incompatible.

burdenbound · Aug 14, 2013

ultra23 :

No problem, sorry there wasn't an easier solution.

ultra23 · Aug 14, 2013

burdenbound :

ultra23 :

No problem, sorry there wasn't an easier solution.

Thanks, you and photonboy saved me a lot of headache!

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