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PWM Related fan control question

post #1 of 36
Thread Starter 
Hello Everyone,

So I'm working on my first foray into water cooling my computer. So my question is this...

I have a Rheosmart6, and a Rampage IV Black. After I got the controller, I tested the PWM function of the RIVBE, and it works the way I want it to. I want to control all my fans off the Rheosmart6 (18 AP-15s). Would it be okay to control the fans attached to the radiators for the GPUs from PWM control for the CPU? I have no problem manually controlling some fans, but I would like to have everything be automatic.

The Build

Already have:

Corsair 900D
Intel i7-4930K
Asus Rampage IV Black Edition
Kingston HyperX Beast 64gb
Asus GTX 780ti Reference SLi
Samsung 840 evo 256 SSD
Western Digital 500gb Black HDD
Sunbeam Rheosmart6
Seasonic X-1250
Alphacool UT60 480mm x2
Alphacool ST30 240mm
All EK blocks and backplates
Swiftech MCP655-PWM x2
EK dual D5 pump top and Res
20 Scythe AP-15s

I still need to decide on tube and fittings, and I'll post pictures later of everything I got.

This is a gaming rig that will be used with my home lab for certifications.
post #2 of 36
I have a 45w fan controller and I don't use it. I prefered PWM control over fan controller any day of the weeks. I set it at around 26% in the bios which is around 2400rpm fan speed and ramp it up to 5000rpm at load. I am running 3 Black Ice GTX radiators, 480mm, 2 360mm on 10 Delta fan 5500rpm pwm. 2 80mm x38 @9000rpm pwm front vrm and 2 4000rpm pwm back vrm. All these fans controlled via pwm. PWM fan sound different and better.
post #3 of 36
The Rheosmart 6 will handle up to 30watts per channel. The AP-15's pull 0.083A each.. or about 1 watt (0.996) each. P(W) = I(A) × V(V). They do have a 3 to 5 watt startup requirement typically.. so figure that in when allocating fans.

you can use some fan ports to hook the fans too.. and then hook those to the controller. Like these: http://www.frozencpu.com/products/14662/ele-988/3-Pin_Power_Distribution_PCB_5xWay_Block_MMT-PCB-5WAY.html?tl=g47c121s424

Big selection of ports.. you can pick what you like: http://www.frozencpu.com/cat/l3/g47/c121/s424/list/p1/Fan_Accessories-Fan_Accessories-Multi_Fan_Ports-Page1.html

As you can see from this pic : http://ecx.images-amazon.com/images/I/51if%2BbbS8jL.jpg, The Rheosmart 6 is not a true PWM compatible controller... in the sense that it only has 3 pin connectors for the fans, not 4-pin.... so cannot send a PWM signal to them. But the Mobo PWM can tell the Rheosmart how much juice / how often to send to the fans based on the single PWM connector on the controller. Basically... that means that the fan ports should work fine, since they are 3-pin like the connectors on the controller.

Does that help?
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post #4 of 36
Thread Starter 
Thanks for the responses....
Quote:
Originally Posted by BruceUSA View Post

I have a 45w fan controller and I don't use it. I prefered PWM control over fan controller any day of the weeks. I set it at around 26% in the bios which is around 2400rpm fan speed and ramp it up to 5000rpm at load. I am running 3 Black Ice GTX radiators, 480mm, 2 360mm on 10 Delta fan 5500rpm pwm. 2 80mm x38 @9000rpm pwm front vrm and 2 4000rpm pwm back vrm. All these fans controlled via pwm. PWM fan sound different and better.

What are you cooling what that setup? My concern is if my GPUs are working harder than the CPU, will the fans cool the GPUs enough while being controlled by the CPU for the whole loop?.

Quote:
Originally Posted by cgipson1 View Post

The Rheosmart 6 will handle up to 30watts per channel. The AP-15's pull 0.083A each.. or about 1 watt (0.996) each. P(W) = I(A) × V(V). They do have a 3 to 5 watt startup requirement typically.. so figure that in when allocating fans.

you can use some fan ports to hook the fans too.. and then hook those to the controller. Like these: http://www.frozencpu.com/products/14662/ele-988/3-Pin_Power_Distribution_PCB_5xWay_Block_MMT-PCB-5WAY.html?tl=g47c121s424

Big selection of ports.. you can pick what you like: http://www.frozencpu.com/cat/l3/g47/c121/s424/list/p1/Fan_Accessories-Fan_Accessories-Multi_Fan_Ports-Page1.html

As you can see from this pic : http://ecx.images-amazon.com/images/I/51if%2BbbS8jL.jpg, The Rheosmart 6 is not a true PWM compatible controller... in the sense that it only has 3 pin connectors for the fans, not 4-pin.... so cannot send a PWM signal to them. But the Mobo PWM can tell the Rheosmart how much juice / how often to send to the fans based on the single PWM connector on the controller. Basically... that means that the fan ports should work fine, since they are 3-pin like the connectors on the controller.

Does that help?

That's exactly how I plan on connecting everything. I just need to figure out cable lengths and mounting the fan distribution. However I do understand the limitation of the Rheosmart6. My test was with a few AP-29s hooked up to the CPU_OPT, and some Prime95 to see if the controller would regulate the fans along side the temporary CPU cooler. It worked, and now I'm wondering if I could manually control the fans on the rads for the GPUs or let the CPU control everything.

Also the AP-15 hava about 4.36w at start-up. I only plan to run at most 4 per channel. I could run all my fans including the case fans to the controller, but I'll let the Mobo control those for Gits and Shiggles.
Edited by Contagious Specialist - 3/11/14 at 5:03pm
post #5 of 36
Quote:
Originally Posted by Contagious Specialist View Post

Thanks for the responses....
What are you cooling what that setup? My concern is if my GPUs are working harder than the CPU, will the fans cool the GPUs enough while being controlled by the CPU for the whole loop?.
That's exactly how I plan on connecting everything. I just need to figure out cable lengths and mounting the fan distribution. However I do understand the limitation of the Rheosmart6. My test was with a few AP-29s hooked up to the CPU_OPT, and some Prime95 to see if the controller would regulate the fans along side the temporary CPU cooler. It worked, and now I'm wondering if I could manually control the fans on the rads for the GPUs or let the CPU control everything.

Also the AP-15 hava about 4.36w at start-up. I only plan to run at most 4 per channel. I could run all my fans including the case fans to the controller, but I'll let the Mobo control those for Gits and Shiggles.

Unless you can run temp sensor leads off the GPUS to the motherboard, the mobo will have no way to knowing what the GPU temps are, and when to crank those fans! But the AI Suite Fan Expert that comes with the mobo works pretty well, and you can set profiles there or just control them manually (I would not use the overclocking part of it though... it is flaky). If you put them on the controller.. just turn a knob...lol!
Edited by cgipson1 - 3/11/14 at 7:02pm
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post #6 of 36
Right now, I am only cooling the CPU at my sig. But I have plan at later date to add 2 r9 290 .



PS. In your situation, depends how you route your loop. But if you place a radiator after the water block, then you should run the fan on that radiator on a fixed rpm and use your fan controller to that. That way you will have constants fan speed at your desired.
Edited by BruceUSA - 3/11/14 at 7:08pm
post #7 of 36
Thread Starter 
Quote:
Originally Posted by cgipson1 View Post

Unless you can run temp sensor leads off the GPUS to the motherboard, the mobo will have no way to knowing what the GPU temps are, and when to crank those fans! But the AI Suite Fan Expert that comes with the mobo works pretty well, and you can set profiles there or just control them manually (I would not use the overclocking part of it though... it is flaky). If you put them on the controller.. just turn a knob...lol!

I can, and this is a thought of mine to do so with an inline temp sensor coming out of the GPUs. I also have a Lamptron touch in my other system that I could use if I wanted to and use that to do temp controlled fan profiles, but I want to give the Rheosmart a shot.
Quote:
Originally Posted by BruceUSA View Post

Right now, I am only cooling the CPU at my sig. But I have plan at later date to add 2 r9 290 .

I totally looked over your sig when I read that, but I wanted to go with R9s, but overall price was a factor and when I got everything, 780tis were cheaper.
post #8 of 36
Thread Starter 
So I've been doing some testing since I got my loop finished (First custom water cooling setup, first try, no leaks). I've been running all my fans off of the PWM signal from the CPU. I couldn't find any difference manually controling, using temp based from my Lamptron Touch, and PWM from the Rheosmart 6. With that being said, I'm using the Rheosmart. In FanXpert 2, I set the fan control to be a little more aggressive since my look goes...

Pump>Rad>GPU>GPU>Rad>CPU>Res.

The only changes I had to make from my original post is that I'm only running 2 UT60 480mm rads. I wansn't able to fit the 240mm rad because I'm running push/pull.

CPU and GPUs at stock clock

post #9 of 36
Quote:
Originally Posted by BruceUSA View Post

I have a 45w fan controller and I don't use it. I prefered PWM control over fan controller any day of the weeks. I set it at around 26% in the bios which is around 2400rpm fan speed and ramp it up to 5000rpm at load. I am running 3 Black Ice GTX radiators, 480mm, 2 360mm on 10 Delta fan 5500rpm pwm. 2 80mm x38 @9000rpm pwm front vrm and 2 4000rpm pwm back vrm. All these fans controlled via pwm. PWM fan sound different and better.

Holy Schmolly ..... ever throw a decibel meter on that thing ? smile.gif

The H100i breaks 60dBA at 2600 rpm and I can't stand to be in the same room with them....

Some PWM fans can be hampered by that annoying clickety noise.



Quote:
Originally Posted by Contagious Specialist View Post

So I've been doing some testing since I got my loop finished (First custom water cooling setup, first try, no leaks). I've been running all my fans off of the PWM signal from the CPU. I couldn't find any difference manually controling, using temp based from my Lamptron Touch, and PWM from the Rheosmart 6. With that being said, I'm using the Rheosmart. In FanXpert 2, I set the fan control to be a little more aggressive since my look goes...

Pump>Rad>GPU>GPU>Rad>CPU>Res.

The only changes I had to make from my original post is that I'm only running 2 UT60 480mm rads. I wansn't able to fit the 240mm rad because I'm running push/pull.

CPU and GPUs at stock clock


I have been experimenting with FanXpert2 for about 5 months on the system in my siggie...... thinks I have looked at:

PWM control
Hybrid PWM Control - Phanteks Fan PCB takes a PWM signal and uses it to control up t o eleven 3 pin variable voltage fans
Variable Voltage Control
Manual Control - Via Reeven Six Eyes
BIOS Control
FanXPert2 Control

After over 100 hours of experimentation, I have to admit, from a user experience / performance standpoint it is a complete waste of time. Not that that I didn't enjoy the challenge and enjoyment of figuring out optimal settings ..... but before I saw why in one sense it was a waste of time, I'll tell ya what I found:

1. BIOS control is crappy compared to FanXpert2
2. The is no discernable difference between PWM control or variable voltage control with respect to temps or sound.
3. I'm not interested in manual control..... I use the Six Eyes solely for temperature monitoring (420 Rad in, 420 Rad Out, 280 Rad in, 280 Rad Out, Ambient Air, Case Air.
4. The hybrid PWM control presents the best of both worlds ..... takes a PWM signal and sends it to 11 three pin fans saving ya about $5 per fan and not sacrificing anything. It also eliminates the PWM clicky noise as the action which causes the noise happens at the PCB instead of the fan.

My system produces a Delta T @ 8.4C at 1236 rpm ..... but the fans are audible at 900 rpm and up. CPU never breaks 74C (4.6GHz under stress test) and GPus hit 39 or 40C under Furmark. I set up fan curves in FanXpert2 to stay from 325 - 850 for all temps up to 65C and so far it has not exceeded that under any activity..... at 74C it gets up to about 925 rpm under CPU stress test.

So getting back to why it is in a sense "a waste of time", it's this......

1. Nothing I can run on the machine (other than CPU synthetics) even stress tests like RoG Bench is capable of taking the system above 850 rpm.
2. The system is completely dead silent at up to almost 900 rpm.

Given 1 and 2 above, what is the point of controlling fan speeds, why not just set at 850 rpm and forget about it ?

Obvious answer .... I'm a geek and I enjoy the experimenting and seeing what effect various changes have on the system. The data has been useful in dispelling a few myths and supplies info for sizing components for new systems.

Given the fact that you are at stock and have 606 watts of cooling (two 480s in push pull) at 1250 rpm to my 420 watts (in push only) w/ twin 780s at 25% OC, I expect you could have ya fans top out at 650 rpm and still maintain a Delta T of 10C.
Edited by JackNaylorPE - 3/23/14 at 5:41pm
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post #10 of 36
Thread Starter 
Quote:
Originally Posted by JackNaylorPE View Post

Some PWM fans can be hampered by that annoying clickety noise.
I have been experimenting with FanXpert2 for about 5 months on the system in my siggie...... thinks I have looked at:

PWM control
Hybrid PWM Control - Phanteks Fan PCB takes a PWM signal and uses it to control up t o eleven 3 pin variable voltage fans
Variable Voltage Control
Manual Control - Via Reeven Six Eyes
BIOS Control
FanXPert2 Control

After over 100 hours of experimentation, I have to admit, from a user experience / performance standpoint it is a complete waste of time. Not that that I didn't enjoy the challenge and enjoyment of figuring out optimal settings ..... but before I saw why in one sense it was a waste of time, I'll tell ya what I found:

1. BIOS control is crappy compared to FanXpert2
2. The is no discernable difference between PWM control or variable voltage control with respect to temps or sound.
3. I'm not interested in manual control..... I use the Six Eyes solely for temperature monitoring (420 Rad in, 420 Rad Out, 280 Rad in, 280 Rad Out, Ambient Air, Case Air.
4. The hybrid PWM control presents the best of both worlds ..... takes a PWM signal and sends it to 11 three pin fans saving ya about $5 per fan and not sacrificing anything. It also eliminates the PWM clicky noise as the action which causes the noise happens at the PCB instead of the fan.

My system produces a Delta T @ 8.4C at 1236 rpm ..... but the fans are audible at 900 rpm and up. CPU never breaks 74C (4.6GHz under stress test) and GPus hit 39 or 40C under Furmark. I set up fan curves in FanXpert2 to stay from 325 - 850 for all temps up to 65C and so far it has not exceeded that under any activity..... at 74C it gets up to about 925 rpm under CPU stress test.

So getting back to why it is in a sense "a waste of time", it's this......

1. Nothing I can run on the machine (other than CPU synthetics) even stress tests like RoG Bench is capable of taking the system above 850 rpm.
2. The system is completely dead silent at up to almost 900 rpm.

Given 1 and 2 above, what is the point of controlling fan speeds, why not just set at 850 rpm and forget about it ?

Obvious answer .... I'm a geek and I enjoy the experimenting and seeing what effect various changes have on the system. The data has been useful in dispelling a few myths and supplies info for sizing components for new systems.

Given the fact that you are at stock and have 606 watts of cooling (two 480s in push pull) at 1250 rpm to my 420 watts (in push only) w/ twin 780s at 25% OC, I expect you could have ya fans top out at 650 rpm and still maintain a Delta T of 10C.

Thanks for your input. I took all this into consideration while testing out cooling with my overclock.

Well after some overclocking I was able to get a stable 4.5 GHz at 1.4 volts, and 1200 MHz on the GPUs. After playing around with the fan speeds, I have a hard time getting the CPU above 65c even at the lowest RPMs my fans will do. The GPUs hardly ever break 43c. I feel like there is more left in the GPUs. So far I am happy with the pumps being controlled by the CPU, and leaving the fans at a very quiet 650-850 rpm manual setting. The only other changes I plan on making cooling wise is to spread the fans out more along the channels. I'm doing this because I'm moving the case fans back to Mobo control.

The bad news about all this is the Rheosmart 6 blew out this morning. I have my Lamptron Touch that I'm going to install and RMA the Rheosmart. I'll keep the Rheosmart as a backup, and use the Lamptron. I'm under the impression that I can add another GPU and my loop will handle it just fine.

Overall I think you're right. PWM can be a waste. My next idea was to control the fans on the first rad going to the GPUs by the GPU's PWM header. Full cover blocks will destroy this idea, but since I'm moving on to another computer to water cool with my extra parts, I'll try it on that build.
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