[SOLVED] Connecting 3-pin fans to a 4-pin fan hub ?

[floorcleaner]

If i connect this fan hub to the system fan header, will all case fans with 3 pins connected to it rotate at maximum speed, or will my system control the speed like shown here?

 

[taeioum]

Very good question! The 4th pin is the pin that allows your motherboard to vary the speed, so all 3-pin fans run at 100%.

 

[floorcleaner]

Very good question! The 4th pin is the pin that allows your motherboard to vary the speed, so all 3-pin fans run at 100%.

Thank you! As you can see, my PC appears to be controlling the system fan speed. I connected two fans using this splitter, which came with the fans. But if i use the hub, my pc won't be able to control fan speed?

 

[Colif]

if you attach dc - 3 pin fans - to a hub that can run pwm fans - 4 pin - the motherboard cannot see the fan speeds and will run all fans at same speed. I know as I was for about 2 years until just last week, its only since replacing the fans with PWM that I can see the speed... not that it helps as all fans on it run at same speed. But its better than nothing.

 

[floorcleaner]

if you attach dc - 3 pin fans - to a hub that can run pwm fans - 4 pin - the motherboard cannot see the fan speeds and will run all fans at same speed. I know as I was for about 2 years until just last week, its only since replacing the fans with PWM that I can see the speed... not that it helps as all fans on it run at same speed. But its better than nothing.

Is it ok to leave all fans running at their maximum speed of 1200 rpm? If so, I'll just get the hub and connect three more fans.

 

[SkyNetRising]

I'll just get the hub and connect three more fans.

Just change your fans to 4pin PWM fans.

 

[floorcleaner]

Just change your fans to 4pin PWM fans.

After a bit of googling, I found out that I can control the fan speed manually if I change it to DC mode. So if i change the system header voltage in the bios, all the fans connected to it can be controlled, right? or using this app. All PWM fans are very expensive. This is the cheapest one I can find.

 

[taeioum]

True, that application can do that. But only with PWM fans. That application still addresses the fans through the 4th pin, which your fans don't have.

 

[floorcleaner]

True, that application can do that. But only with PWM fans. That application still addresses the fans through the 4th pin, which your fans don't have.

I connected my front and rear 3 pin case fans to the system fan header on the motherboard , and when i set the rpm range to 0 on the app, both the fans stopped spinning. So, technically, if i connect the fan hub to the sys fan header, all fans connected to that hub can be controlled as one using this app, right?

 

[taeioum]

If the former works, the latter should too. I guess you won't know until you try it.

Maybe when you set it to 0 it just stops all power to the fan header, but 3-pin fans should in no way have variable speeds. So it seems like it's an "all or nothing" situation.

 

[floorcleaner]

If the former works, the latter should too. I guess you won't know until you try it.

Maybe when you set it to 0 it just stops all power to the fan header, but 3-pin fans should in no way have variable speeds. So it seems like it's an "all or nothing" situation.

You are right, the fan stopped when i set it to 30% or below. I'll just buy the hub and give it a try, and if it doesn't work, ill return it haha. Thank you.

 

[taeioum]

You are right, the fan stopped when i set it to 30% or below. I'll just buy the hub and give it a try, and if it doesn't work, ill return it haha. Thank you.

No problemo, glad to help. Good luck!

 

[floorcleaner]

No problemo, glad to help. Good luck!

I just realised the hub receives power from sata and there is no way to vary the voltage using the app. I should get a 4 pin fan or use the 3 pin fan at full speed using the hub.
🤦‍♂️
The sys fan header can deliver up to 1 amp and 12 watts max, and the fan only needs 0.16 amps and 1.96 watts. So one header should support four fans without any problem if i use this, right?
0.16ampsx4=0.64amps
1.92wattsx4=7.68watts

 

[Paperdoc]

You're getting close.

START with this: Control of fans is different, depending on whether they are 3-pin or 4-pin. A mobo fan header usually can be set to one way or the other, but it cannot control both fan types together. So IF you have both types, you must find a way to make two groups of them with Splitters, etc. - one group of 4-pins on one header configured to control them, and a second group of 3-pins on a different header set for the other way.

NEXT, recognize there is a difference between a SPLITTER and a HUB. The first item you linked to that looks like a circuit board is a HUB. It works ONLY with 4-pin fans, and must be connected to a header using the newer PWM Mode of control. It gets all power for its fans from the PSU so it is not limited by the header.

In your last post of Dec. 29 you linked to a SPLITTER from DeepCool that looks like a small box with ports. It gets all power for its fans from the host header - does NOT have any connection to the PSU - and thus is limited to a max load of 1.0 A total for all fans connected to it. This IS the right device to use with 3-pin fans because it passes to its fans the controlled VOLTAGE from the host header. PLUS, that header needs to be set to Voltage Control Mode (aka DC Mode), which you have been using with success with 3-pin fans. You say the fans you have are all 3-pin with max current draw spec of 0.16 A - that's a normal number for that fan type. So hypothetically you could connect up to 6 fans of that type to one mobo header, using two or more Splitters if necessary. I don't think you have that many.

NOTE this. Any fan header can deal with the speed signal sent back to it from only ONE fan. So that Splitter will only send back the speed signal from the fan plugged into Port #1, and ignore the others. You must plug one fan into Port #1.

 

[floorcleaner]

You're getting close.

START with this: Control of fans is different, depending on whether they are 3-pin or 4-pin. A mobo fan header usually can be set to one way or the other, but it cannot control both fan types together. So IF you have both types, you must find a way to make two groups of them with Splitters, etc. - one group of 4-pins on one header configured to control them, and a second group of 3-pins on a different header set for the other way.

NEXT, recognize there is a difference between a SPLITTER and a HUB. The first item you linked to that looks like a circuit board is a HUB. It works ONLY with 4-pin fans, and must be connected to a header using the newer PWM Mode of control. It gets all power for its fans from the PSU so it is not limited by the header.

In your last post of Dec. 29 you linked to a SPLITTER from DeepCool that looks like a small box with ports. It gets all power for its fans from the host header - does NOT have any connection to the PSU - and thus is limited to a max load of 1.0 A total for all fans connected to it. This IS the right device to use with 3-pin fans because it passes to its fans the controlled VOLTAGE from the host header. PLUS, that header needs to be set to Voltage Control Mode (aka DC Mode), which you have been using with success with 3-pin fans. You say the fans you have are all 3-pin with max current draw spec of 0.16 A - that's a normal number for that fan type. So hypothetically you could connect up to 6 fans of that type to one mobo header, using two or more Splitters if necessary. I don't think you have that many.

NOTE this. Any fan header can deal with the speed signal sent back to it from only ONE fan. So that Splitter will only send back the speed signal from the fan plugged into Port #1, and ignore the others. You must plug one fan into Port #1.

Wow, thank you so much for explaining everything clearly.

 

[Paperdoc]

You're welcome and good luck. Thanks for Best Solution.