Jump to content

Active 4pin PWM fan splitter

RejZoR
By RejZoR
in Cooling
 Share
Posted
7 hours ago, RejZoR said:

All 3 SYSFAN headers, despite being PWMs don't do anything so all fans end up spinning at max speed no matter what you set it at. 

the slight rattling of the water pump is the loudest part in the system...

What you mean is that they're 4pin headers but sys_fan headers don't support pwm since the last pin isn't used. 

There may be quieter pumps but air cooling is ultimately quieter if you're prioritizing silence. 

If you ever need help with a build, read the following before posting: http://linustechtips.com/main/topic/3061-build-plan-thread-recommendations-please-read-before-posting/
Also, make sure to quote a post or tag a member when replying or else they won't get a notification that you replied to them.

Link to comment
Share on other sites
Link to post
Share on other sites
Posted
  • Author
53 minutes ago, WoodenMarker said:

What you mean is that they're 4pin headers but sys_fan headers don't support pwm since the last pin isn't used. 

There may be quieter pumps but air cooling is ultimately quieter if you're prioritizing silence. 

But when I connect a single 4pin PWM fan to SYSFAN headers, the RPM control does work as intended with PWM. As soon as it goes through this fan hub, it gets locked to 100% for some reason. Do you really think all 4pin headers are actually DC ?! Why would you use 4pin headers then!? Just to confuse user?

Link to comment
Share on other sites
Link to post
Share on other sites
Posted
7 minutes ago, RejZoR said:

But when I connect a single 4pin PWM fan to SYSFAN headers, the RPM control does work as intended with PWM. As soon as it goes through this fan hub, it gets locked to 100% for some reason. Do you really think all 4pin headers are actually DC ?! Why would you use 4pin headers then!? Just to confuse user?

It could just be easier to leave the 4th pin there but unused during manufacturing or it could just look good in marketing. It's dc only. In either case, the 4th pin which is required for pwm is non functional on this motherboard's sys_fan headers. 

If you ever need help with a build, read the following before posting: http://linustechtips.com/main/topic/3061-build-plan-thread-recommendations-please-read-before-posting/
Also, make sure to quote a post or tag a member when replying or else they won't get a notification that you replied to them.

Link to comment
Share on other sites
Link to post
Share on other sites
Posted

When using splitters you need to have only ONE speed signal from ONE fan going to the board, de-pin the speed signal from the other fans on the splitters and you should get rid of the dirty speed signal. If you watch fan speeds you'll see the speed signal going all over the place because it's a bunch of slightly different signals changing the speed the board is seeing so it's constantly hunting the PWM control up and down to get the speed right. I had the same problems back in the day on 3 pin fans with splitters, it's the same kind of speed signal and the solution was the same. Give that a try, otherwise an active fan hub is an excellent solution and MUCH cleaner than splitters galore plus you can safely run much stronger fans later if you want to.

Link to comment
Share on other sites
Link to post
Share on other sites
Posted
On 12/12/2019 at 4:15 AM, RejZoR said:

So, I bought this one:

https://www.aliexpress.com/item/32903324952.html

 

Received it just now, installed it, connected the signal cable to the SYSFAN1, connected 1 fan to red connector and the rest to black ones. All fans are PWM and of same type. RPM of fans is always maxed regardless of what I set in motherboard BIOS. WTF?! It's like PWM signal goes nowhere. It is reading the correct fan RPM though. What the hell am I doing wrong or is this thing just fake PCB that literally does nothing with PWM signal routing. Weird.

 

EDIT:

Turns out stupid MSI X99A Gaming 7 board only sends PWM RPM command from the CPU header. All 3 SYSFAN headers, despite being PWMs don't do anything so all fans end up spinning at max speed no matter what you set it at. Slow clap MSI. Slow clap. So now I have case fans on CPU header and CPU fan on SYSFAN header. Coz logic...

 

Resonating fans at variable RPM are also gone now, apparently this excellent board didn't like fans being hooked through Y splitter as it was causing some electrical problems and made fans resonate weird. Now on this hub, nothing. Now I have a different problem. In idle, fans are basically inaudible and the slight rattling of the water pump is the loudest part in the system...

My Asus H87 board has the same issue, sys fan is a 4 pin header but fan control is NOT PWM! I have a silverstone hub connected to the CPU header for speed signaling and control signal and the case fans running with CPU speed. It's not ideal but it's working for one of my ITX systems.

 

Does the one you bought control the fans correctly when it's on the CPU fan 4 pin header? I'm looking for another fan hub for my new build and want to keep the wiring cleaner.

Link to comment
Share on other sites
Link to post
Share on other sites
Posted
  • Author

I've rewired and found out this motherboard has terrible fan management.

 

Before I had Y splitters on all the headers and I just used them all to power all the fans. And if I didn't use fixed speeds on most of them (and used curve instead) they were doing weird resonating thing that drove me insane). Since only CPU1 fan actually sent PWM signal, I had to turn everything around and place this PWM fan hub on CPU1, I had AiO pump on CPU2 and the actual CPU fan on SYSFAN1.

 

Now, I've rotated all that and placed actual CPU fan on CPU1, PWM fan hub on CPU2 and AiO pump on SYSFAN1. The funny thing is, CPU2 apparently only knows curve and you can't even set it to fixed custom value. It's either curve (that I'd have to fake to horizontal line at certain % to have a fixed desired % speed) or turning it off which means 100% speed. What moron designed fan management on this board, jesus, now I'm starting to see why it was so much cheaper compared to ASUS X99 Sabertooth that I had before and which unfortunately died. That one had so much better fan control, all headers were apparently actually PWM and you could switch them into DC if needed and things actually worked as displayed. Here, everything is freaking wonky and weird.

 

And when I managed to adjust everything to account for all the weirdness (now that I moved AiO pump from the weird CPU2 header, I could eliminate rattling by lowering pump speed at lower CPU utilizations), the whole motherboard fan control logic just decided not to ramp things up when I was testing. Ran IntelBurnTest and RTHDRIBL at the same time and temps were climbing up to 85°C which is not unusual for my super quiet setup, but this was too quiet. Fans didn't ramp up based on curve at all. And god knows what pump was doing. So, motherboard just decided not to obey the curves I've set and just ran at lowest RPM until whole system BSOD-ed because it was getting too hot.

 

One thing is for sure, I won't be getting MSI motherboard next time. What a weird ass product full of glitches and their BIOS updates are so sporadic and also full of bugs and glitches. WTF

Link to comment
Share on other sites
Link to post
Share on other sites
  • 3 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing Cooling

×