Fan Control Questions

[BoredErica]

First: 
I apologize if this topic has been covered multiple times. It's also a little unclear which subsection to post this in since I'm dealing with fans, but in quantities that would only make sense on a water cooling setup. I am planning a water cooling setup that will require ~27 fans.

 

Motherboards have fan headers on them, and even if they are 4 pin they might control voltage only instead of PWM. No matter which method, many motherboards have the ability to control fan speed based on load or temperature. No motherboard has 27 fan headers so here is where it gets tricky. I could use splitters, which I believe splits the power to two connections. So if a motherboard can only dish out, say, 5W, each connector will be 2.5W. This means by splitting I am lowering the maximum speed of each fan. If I have a single fan hooked up to a splitter with the other connection empty, it should be 5W to the one fan. My assumption (and correct me if I'm wrong) is that when split, if a motherboard feels the fan connected to the fan header should be getting 3W instead of 1W due to higher load, instead of one fan getting 3W we will now have two fans getting 1.5W each.

 

I am searching for a way to adjust the fan speed of all of my 27 PWM fans (Silent Wings 3 High Speed). I am concerned about the minimum speed. Right now I have 6 fans connected to a NZXT Sentry Mix 2, and while the max fan speed is screamin', the minimum fan speed is too loud for me. Thermalbench's data suggests the fans should be able to hit a minimum of around 250 RPM and I am quite sure I'm not getting such low RPMs. I suppose one way to bypass this is to hook up splitters, and split the splitters, and split those splitters until each fan gets low enough voltage to hit its minimum before shutting down entirely. But that seems like a very complicated process that gets more complicated with 27 fans and really limits the maximum fan speeds of each fan.

I really don't want some software running to control my fan speed... I was hoping for something automatic and low level, if that makes any sense. I don't have Asus fan software on my computer and I like to install as few programs on my computer as possible. My Noctua ramps up under CPU load automatically fine. I want to figure out what RPM I want on idle after playing with different fan speeds, and what max RPM I want under normal load. But I'd also like (as a bonus) to be able to crank things to 11 if I so choose. I have heard of the Aquaero 6, but I don't know if it has the kind of fine grain control I want. Blazing fast max RPMs is useless without the control to bring it down to inaudible levels when it's time. Finally, I would like to get a decently accurate picture of how fast my fans are running.

It seems to me that motherboards are not a good solution to this. There are just too many fans, and motherboards change through upgrade cycles. I don't want to be forced to pick the same motherboard through every upgrade to try to get my current fan setup to work. The current NZXT Sentry Mix 2 is not working quite as well as I'd like either. For reference, my current board is the z170 Asus Hero.

I am willing to spend money when it leads to the right solution that works... but I don't know if something like the Aquaero is it.

Thank you for any help you can give. 

 

[VVoltor]

Splitters don't reduce voltage. Also, the speed of PWM fans isn't regulated by reducing the voltage but by pulse width modulation. You can't power 27 fans off any motherboard, so you'd have to power them from a PSU molex connection. You might need more than one fan hub.

 

I don't want to say 27 fans is stupidly ridiculous, (although it is) but I can guarantee that setup won't give you the best results possible. More fans = / = quieter operation.

[Majestic]

Splitting the fan wont change the speed. You only cannot exceed the 1 amps. But if you use efficient fans, like Noctua's, you can put multiple fans onto a single header.

Afaik they are like 0.05A each (NF-F12). So in theory, that's 20 fans.

[0ld_Chicken]

I guess there are a few routes you could take.  Like others said, the motherboard wont lower the max speed depending on how many fans are plugged in, but you should not exceed the max amperage for each header (usually 1amp) or you will blow that fan channel out on your mobo.  

 

There are PWM splitters like Silverstones 8way PWM-http://www.silverstonetek.com/product.php?pid=526

   It is POWERED from a sata connector and gets the PWM signal from the motherboard and sends a rpm signal from one fan back to the mobo.  No worries about power draw since all the fans are powered by the sata connector and the mobo only has to put out pwm which is then split to the (up to) 8 fans.  If you've got 4 headers (haven't looked but a good asus usually does) then you could use 4 splittlers run to 4 headers of the mobo with a few empty spots on each splitter. 

 

Or something like the Aquaero 6, lots of PWM power (120w) though all 27 fans at full speed will pull 118.8w (120mm) or 162w (140mm) according to Bequiet.  You may be able to pull off the 140mm but the aquaero temps will have to be closely monitored and it may need liquid cooling.  I've never overloaded my aquaero

• you will still need to find a way to split from 4 headers to 27 fans-I would buy the connectors/pins/cable/sleeving and make some, otherwise it'll be a cable management nightmare

edit: aquaero is definitely the way to go as far as control and options.  Get a water temp sensor and air temp sensor and set it up to work the fans off the liquid-ambient DeltaT.  Great way to control the fans 

[BoredErica]

17 minutes ago, VVoltor said:

Splitters don't reduce voltage. Also, the speed of PWM fans isn't regulated by reducing the voltage but by pulse width modulation. You can't power 27 fans off any motherboard, so you'd have to power them from a PSU molex connection. You might need more than one fan hub.

 

I don't want to say 27 fans is stupidly ridiculous, (although it is) but I can guarantee that setup won't give you the best results possible. More fans = / = quieter operation.

 

17 minutes ago, Majestic said:

Splitting the fan wont change the speed. You only cannot exceed the 1 amps. But if you use efficient fans, like Noctua's, you can put multiple fans onto a single header.

Afaik they are like 0.05A each (NF-F12). So in theory, that's 20 fans.

Thanks for the replies.

Splitters don't reduce the voltage, but the maximum output of a fan header doesn't increase if more fans are hooked up. So if one fan is hooked up straight to a 4pin, I'll get 0.05A. If 1 fan is hooked up to a splitter, that's 0.05A to 1 fan for 0.05A total. If 2 fans are hooked up to a splitter then that's 0.05A to each fan, for 0.1A total. And if a splitter is hooked up to a 4 pin, and on one end is a fan, the other end is another splitter with both ends having a fan, that's 0.05A for each fan for a total of 0.15A. I believe this is correct.

VVoltor brought up the fact that PWM fans aren't regulated by reducing the voltage. I believe PWM fans can be regulated by voltage or PWM, with PWM being the better option generally. The voltage situation seems clear to me now. So what if it's being controlled by PWM and I use a splitter or two on the 4pin on the motherboard? If the motherboard thinks the fan should be running at 1000 RPM will all the fans be 1000 RPM if I start using splitters?
 

How would I power 27 fans via molex? I'm assuming there's some kind of splitter with molex for power.

Finally, about 27 fan fans being too many: The idea isn't simply that more fans = quieter operation. All other things equal having more fans will just make things louder. But I would like to have the fans not be going too fast if I can help it. The idea is to run 3x560mm radiators outside of my case, and have some fans in the case for airflow for VRMs on the motherboard. Although, 3 fans for just motherboard VRMs might be a bit overkill, and those are the fans closest to me (and will therefore sound the loudest).

[BoredErica]

29 minutes ago, 0ld_Chicken said:

I guess there are a few routes you could take.  Like others said, the motherboard wont lower the max speed depending on how many fans are plugged in, but you should not exceed the max amperage for each header (usually 1amp) or you will blow that fan channel out on your mobo.  

 

There are PWM splitters like Silverstones 8way PWM-http://www.silverstonetek.com/product.php?pid=526

   It is POWERED from a sata connector and gets the PWM signal from the motherboard and sends a rpm signal from one fan back to the mobo.  No worries about power draw since all the fans are powered by the sata connector and the mobo only has to put out pwm which is then split to the (up to) 8 fans.  If you've got 4 headers (haven't looked but a good asus usually does) then you could use 4 splittlers run to 4 headers of the mobo with a few empty spots on each splitter. 

 

Or something like the Aquaero 6, lots of PWM power (120w) though all 27 fans at full speed will pull 118.8w (120mm) or 162w (140mm) according to Bequiet.  You may be able to pull off the 140mm but the aquaero temps will have to be closely monitored and it may need liquid cooling.  I've never overloaded my aquaero

• you will still need to find a way to split from 4 headers to 27 fans-I would buy the connectors/pins/cable/sleeving and make some, otherwise it'll be a cable management nightmare

edit: aquaero is definitely the way to go as far as control and options.  Get a water temp sensor and air temp sensor and set it up to work the fans off the liquid-ambient DeltaT.  Great way to control the fans 

Thanks for the information! I see now that too much draw can blow out the fan channel. That is good to know. As stated earlier, my main concern with the Aquaero 6 is the ability for it to control the PWM signal/voltage down to close to the minimum fan speed of the fan (~250 RPM). That's something I thought I was getting when I bought my NZXT Sentry Mix 2. I'm assuming the Aquaero has much finer control in the entire RPM range than the cheap Mix 2. The other concern I have is about automatic fan control... If I could set it up to '600RPM idle, 1200 RPM on load'. It doesn't need to be a curve, just an either or kind of thing. Maybe a button that quickly changes the fan speed to a certain level, but automatic would be best, preferably without having to install some software on my computer.

With 3x560mm radiators in PP that's 8x3 = 24 fans, add 2 for the motherboard VRM. Okay, 26 fans is not a big difference from 27 fans lol.

As for making the cables to make a splitter that works for 27 fans, *shudders*

[0ld_Chicken]

Just now, Dark_wizzie said:

Thanks for the information! I see now that too much draw can blow out the fan channel. That is good to know. As stated earlier, my main concern with the Aquaero 6 is the ability for it to control the PWM signal/voltage down to close to the minimum fan speed of the fan (~250 RPM). That's something I thought I was getting when I bought my NZXT Sentry Mix 2. I'm assuming the Aquaero has much finer control in the entire RPM range than the cheap Mix 2. The other concern I have is about automatic fan control... If I could set it up to '600RPM idle, 1200 RPM on load'. It doesn't need to be a curve, just an either or kind of thing. Maybe a button that quickly changes the fan speed to a certain level, but automatic would be best, preferably without having to install some software on my computer.

With 3x560mm radiators in PP that's 8x3 = 24 fans, add 2 for the motherboard VRM. Okay, 26 fans is not a big difference from 27 fans lol.

The aquaero/aquasuite possibilities are almost endless, I still haven't figured out everything you can do with that stuff... Its incredible.  You should be able to run to the limits of the fan, if they won't do it on an aquaero they probably wont do it.

 

 I checked Thermalbenches review for that fan and looks like they were able to get them to around 250rpm with the aquaero6, though they did note some "issues" with aquaero and pwm control with these fans.  nothing huge but they have a pretty bad curve at the high end and you likely won't have good, fine control in the high rpm ranges.  Will likely drop to 1800rpm with only 1% PWM drop, same story till you get around 1200rpm.  I'm not sure if that would occur with mobo control or not.  The DC control is better at high rpms, but won't drop below ~500rpm

 

As far as the automatic control, thats definitely possible.  Might be easier to set it up on a "curve" but they make it very easy.  Put in  min/max temp, and min/max speeds and it makes the curve for you.  You can shape it automatically using that slider to move the curve along the temp scale, effectively delaying the curve or quickening it.  You can base that on whatever temp(s) you like and control multiple fan channels from a single curve (no need to duplicate).  I like the curve because then you never hear any changes when you base it on water temps.  If you have it as a "idle-load" type deal, then when you're using medium loads then fans will likely switch back and forth as they speed up and cool things below the "load" setpoint.

 

The greatest thing is that once you set your curves and program everything, you don't have to have the program open.  If you really don't want to install software at all, then get the version with a screen and you can program it entirely from the aquaero and never install anything.  That will limit it's ability to pull component temps from the PC but if you are only using water/air temps they can be plugged directly into the aquaero.  I only open mine to make changes, you may be able to uninstall the main aquasuite program but I'm not 100% sure.  If you want component temps there is some sort of "background" service that will run

 

 

[NoobCase]

I will agree with @0ld_Chicken an aquareo or two is the way to go. I have th 5 and planning to get a 6 at some point to get more pwm headers. The software has endless possibilities