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Asus Q-fan control and 3-pin fans

Dec 30, 2004
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Is everyone on PWM fans these days? My 3 pin fans were working fine on my other mobo :(

can't seem to get any level of software control (Q-fan, speedfan) to voltage-control the 3-pin fans I have.

In spite of there being no option in my Speedfan for DC-mode (vs PWM) I did get speedfan to control them once, but haven't been able to replicate after Asus Fan Xpert took control from speedfan and wrote something to BIOS...
 
Dec 30, 2004
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so apparently CPU fan headers these days run at 100% (3-pin) unless it's 4-pin with PWM as a safety mechanism
 

Flapdrol1337

Golden Member
May 21, 2014
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yeah, the cpu fan only does pwm, but there's a good chance one on more of your other fan headers can control the fan with voltage.

if the fancontrol of chassis fans is enabled in the bios you can't control them with speedfan. if you really want speedfan you have to turn it off, but you can also make a nice temp speed curve in the bios.
 
Dec 30, 2004
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yeah, the cpu fan only does pwm, but there's a good chance one on more of your other fan headers can control the fan with voltage.

if the fancontrol of chassis fans is enabled in the bios you can't control them with speedfan. if you really want speedfan you have to turn it off, but you can also make a nice temp speed curve in the bios.
Asus guy on the phone who sounded confident that he knew what he was talking about (I hate it when people do that when they aren't really certain) said that disabling the Q-fan control for the case fans is going to put the fans to 100%. Which is weird because I'm pretty sure the only time I got speedfan to work was when Q-fan was disabled.

The reason I want speedfan is the BIOS limits the minimum speed to 60% on the case fans. Way too high! and I don't get a make a nice curve it's just "min speed" "min temp" "max speed" "max temp". I believe it's linear interpolation.
 

Flapdrol1337

Golden Member
May 21, 2014
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Turning it off sets it to the default 100%, but after that you can control it with speedfan.
 
Dec 30, 2004
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Turning it off sets it to the default 100%, but after that you can control it with speedfan.
that doesn't work either.

What does work is leaving Q-Fan enabled, then setting it to "Manual mode. That lets you control it with speedfan-- provided speedfan has those PWM modes set to "Software Control"
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I found a solution--
You can't get around the CPU fan header requiring PWM, but who says you have to plug a noisy fan that actually cools the CPU into the CPU fan header? Since it runs at 100% I plugged in my quietest fan to the CPU fan header, but it's actually just a case fan. The rest of the Chassis fans are on the same voltage plane, but they can be software controlled via IT8721F's PWM3, so I just plugged my actual CPU fan (still 3-pin) into one of those; the rest are chassis fans behind and above the CPU.

Having all the chassis fans spinning in tandem with the CPU fan is great, very quiet during normal operation
 
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OlyAR15

Senior member
Oct 23, 2014
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Why not use the fan control in the Asus AI Suite software? I find it works really well for fan control. Just let it automatically find the slowest and fastest speeds for each fan and you have very good control over fan speeds.
 

BonzaiDuck

Lifer
Jun 30, 2004
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Why not use the fan control in the Asus AI Suite software? I find it works really well for fan control. Just let it automatically find the slowest and fastest speeds for each fan and you have very good control over fan speeds.
I was going to say that after I stumbled over this thread.

I've worked firsthand with two ASUS boards released after May 2011 -- the latest being one of those cheap "end-of-life-cycle" spinoffs. The good board has double CPU-fan ports ("OPT"), and two or three (need to look when I have the time) -- CHA ports with one PWR port.

For these boards there is "Fan Xpert" and high-end ASUS boards have "Thermal Radar." They work WITH the BIOS Q-Fan settings. It is at least one feature of AI Suite for which I find little fault. In fact, the worst problem people have with AI Suite is the "auto overclocking" feature. The "recording" feature is nice. Nothing really wrong with the manual controls for Digi+VRM or even the "EVO" tuning screen which features the auto-overclocking. You can disable features of Suite that don't suit you. I just find the Fan Xpert to be essential -- for me.

But in the BIOS, you can choose between "Turbo," "Standard," "User" and other settings on the fans, and they seem to perform on their own as if you'd created "fan profiles" with Fan Xpert. Fan Xpert works with the "User" setting. If you don't want to install AI Suite, this almost meets expectations for thermal fan control without any adjustment outside of the BIOS. And frankly, once you've built and tested your PC, you only need to use Fan Xpert once or twice for "custom" fan profiles. After that, you could pretty much leave it alone.
 
Dec 30, 2004
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Why not use the fan control in the Asus AI Suite software? I find it works really well for fan control. Just let it automatically find the slowest and fastest speeds for each fan and you have very good control over fan speeds.
because Fan Xpert is really bad software.

and it limits your min fan speed on the chassis fans to about 40%, way too loud. But, this depends on which Fan Xpert version and build you have installed. ??? bad software for sure

for 3 pin fans you get 1 channel-- all fans spin the same speed

now that I've got speedfan set up, this is definitely better than what Fan Xpert provided
 
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OlyAR15

Senior member
Oct 23, 2014
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because Fan Xpert is really bad software.

and it limits your min fan speed on the chassis fans to about 40%, way too loud. But, this depends on which Fan Xpert version and build you have installed. ??? bad software for sure

for 3 pin fans you get 1 channel-- all fans spin the same speed

now that I've got speedfan set up, this is definitely better than what Fan Xpert provided
Not sure what version of Fan Xpert you are using, but in my version, you have control over each individual fan header, and have control over the full range of the fan. You first have to let the system test each individual fan in order for it to determine the fan range, so I wonder if you are skipping this part.

And for 3 pin, you set the fan header to voltage and it should work properly. I don't know if you are hooking up all your case fans to a fan controller, but again, each fan header on the motherboard is controlled individually.
 
Dec 30, 2004
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Not sure what version of Fan Xpert you are using, but in my version, you have control over each individual fan header, and have control over the full range of the fan. You first have to let the system test each individual fan in order for it to determine the fan range, so I wonder if you are skipping this part.

And for 3 pin, you set the fan header to voltage and it should work properly. I don't know if you are hooking up all your case fans to a fan controller, but again, each fan header on the motherboard is controlled individually.
I believe you have a more full featured motherboard. I don't get to set fan header features like voltage etc, and all the chassis fans are connected to the same voltage.

if I had PWM fans I might be able to control them individually, but from what I can see there're only two FETs next to the fan headers.

I'm just glad I didn't need to replace all fans, buy a fan controller, or buy anything at all to deal with mandatory 100% CPU fan speed
 
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BonzaiDuck

Lifer
Jun 30, 2004
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Well, I'll just throw myself in here between OlyAR15 and soccerballtux.

Yes, the top-end ASUS boards allow for individual CHA-FAN control.

And no -- if there is only one profile for all chassis fans, they don't all run at the same speed; they run at the same % duty cycle.

I look at it this way.

When I was a kid, you could get a Schwinn bicycle with a three-speed gear assembly. We used to put these big "long-horn" handlebars on the bikes. Seems to me those bikes were almost as good as today's expensive mountain bike. You could also get your standard 10 or 15-speed derailleur racing bike. You might eventually use all the gears, but it kept your head straight to use fewer of them.

Simple is best; elaborate and elegant options -- gives you more options.

I just don't have to have every fan in my system with its own profile. They function in groups. And to keep things simple, I have a single CPU fan, an exhaust fan that is really a "puller" CPU fan, and two case fans for intake.

I really don't notice any deterioration in my computing life-style with this setup. But I DO like Fan Xpert.

Now apparently, there've been revisions in SpeedFan. I'll have to give it a good look-see. But if you think about it, there might be advantages to using the proprietary software that came with the motherboard and model.

Jus' sayin', Dawg . . . .
 
Dec 30, 2004
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Well, I'll just throw myself in here between OlyAR15 and soccerballtux.

Yes, the top-end ASUS boards allow for individual CHA-FAN control.

And no -- if there is only one profile for all chassis fans, they don't all run at the same speed; they run at the same % duty cycle.

I look at it this way.

When I was a kid, you could get a Schwinn bicycle with a three-speed gear assembly. We used to put these big "long-horn" handlebars on the bikes. Seems to me those bikes were almost as good as today's expensive mountain bike. You could also get your standard 10 or 15-speed derailleur racing bike. You might eventually use all the gears, but it kept your head straight to use fewer of them.

Simple is best; elaborate and elegant options -- gives you more options.

I just don't have to have every fan in my system with its own profile. They function in groups. And to keep things simple, I have a single CPU fan, an exhaust fan that is really a "puller" CPU fan, and two case fans for intake.

I really don't notice any deterioration in my computing life-style with this setup. But I DO like Fan Xpert.

Now apparently, there've been revisions in SpeedFan. I'll have to give it a good look-see. But if you think about it, there might be advantages to using the proprietary software that came with the motherboard and model.

Jus' sayin', Dawg . . . .
there's no duty cycle in an analog, voltage driven fan

as for using Fan Xpert-- an electron is an electron, no?
 

BonzaiDuck

Lifer
Jun 30, 2004
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there's no duty cycle in an analog, voltage driven fan

as for using Fan Xpert-- an electron is an electron, no?
Maybe I was confused about the technical details. Fan Xpert shows either type of fan under its control as a % of maximum speed.
 

BonzaiDuck

Lifer
Jun 30, 2004
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Everyone has "preferences" and "desires."

I used to build computers from modestly-priced parts. I remember the first "real" project used an Intel Tucson motherboard for a last-generation Pentium. I would not have given a minute's thought to overclocking. And since the OEM Gateway systems I'd purchased before that were "plain Vanilla" IBM-beige tower cases, I bought InWin budget cases.

Then I would proceed to complicate things. But it wasn't until early in the last decade that I became an "enthusiast" builder. I seemed to be having a pissing contest with a friend who had jumped on the enthusiast bandwagon. He would buy parts and cooling devices with the intentions of over-clocking, but at the first sign of a BSOD he would return the settings to stock.

My own extravagance arose with purchase of a front-panel fan controller with thermal sensor wires. While my friend was really happy with manual fan adjustments of his fan-legion with a front-panel Rheobus or whatever it was called, I could see that you would want thermal fan-control. But after piddling with the sensors, I gave up on my first attempt.

At some point I remembered another friend's remark about cooking. He was a medical researcher, just finished with school at University of Basil, who had worked summers in Parisian restaurant kitchens. "Simple is best" -- what we know as the KISS principle.

I would waste good money on later fan-controller experiments. NOt a lot of money -- perhaps the total waste was $120 over four years. At one point I made a Springdale motherboard control the CPU fan, but I don't think the onboard features supported much more.

Some of my purchases actually had promise. The Silverstone Commander worked, but you needed an NVidia chipset or (supposedly) an NVidia graphics card. And because of the NVidia-Intel feud -- they never fully perfected the software that made the Commander meet its promise.
So as much as I appreciate the market offerings of more recent years such as the Aquaero 5 controller, I try to design my whole cooling strategy around the motherboard capabilities.

The ASUS boards especially have their Q-Fan feature, ready-made with built-in fan profile options: "Turbo," "Standard," "Silent." And -- "User." With the first three, you don't even need the software. With "User" you only need to use the software once to get the profile you want.

"Simple . . . is Best." "Einfach ist besser." No more fans than necessary for the objective. Control fans in groups. Use the motherboard. Don't buy extra "stuff" if you can achieve the objective without it.
 

Puffnstuff

Lifer
Mar 9, 2005
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On my asus board qfan ran from bios and then set itself and I had no other input about it apart from enabling it. It keeps my cpu cool and during gaming it will spool the cpu fans up to max periodically.
 

BonzaiDuck

Lifer
Jun 30, 2004
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in analog mode (3pin), it's just the voltage percentage of 12v. So 6v would be 50% speed.
Yup.

Apparently and with at least a few generations of ASUS boards, the fan ports offering four pins for PWM use will also allow control of a 3-pin fan off the same port. This is one of the better accomplishments of fan-control with several ASUS boards.
 
Dec 30, 2004
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Yup.

Apparently and with at least a few generations of ASUS boards, the fan ports offering four pins for PWM use will also allow control of a 3-pin fan off the same port. This is one of the better accomplishments of fan-control with several ASUS boards.
this is standard behavior from motherboard manufacturers, Gigabyte's been doing this for quite some time
 

BonzaiDuck

Lifer
Jun 30, 2004
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this is standard behavior from motherboard manufacturers, Gigabyte's been doing this for quite some time
My "bias of limited information." I had only noted seeing positive remarks about the ASUS ports here and elsewhere. It might even have been the ROG forums.
 

BonzaiDuck

Lifer
Jun 30, 2004
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I never thought that thermal fan control was ever this good around middle of the last decade, or -- I didn't perceive it with the boards I was buying. But even then, I could control a Delta 150CFM Tri-Blade 120mm from the CPU_FAN port. If there were other fans on the motherboard ports, they wouldn't have drawn more than an extra ampere in total.

Come to think of it, I've still got that Tri-Blade tucked away in the parts-locker. Hmmm.

Man! That thing was rated at around 50+ dBA! But it really wasn't nearly that bad -- the way it was installed and the way it was used . . . .
 

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