Asus Q-Fan 2 (on P5GD2 motherboard)

Control: management of fans, temp/rpm monitoring via soft/hardware

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Francis
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Asus Q-Fan 2 (on P5GD2 motherboard)

Post by Francis » Tue Feb 01, 2005 6:07 am

Hi!

I recently got a Asus P5GD2 motherboard. I've searched for mention of the Asus "Q-Fan" fan control feature on this forum. However, none specifically mention "Q-Fan 2", which is what this motherboard has. I couldn't find a description of "Q-Fan 2" on the Asus website - you get the same page for "Q-Fan 2" as you do for "Q-Fan", and it seems to be an older page written for "Q-Fan":

http://www.asus.com/support/english/tec ... q-fan.aspx

"Q-Fan 2" does seem to have a new option called "CPU Q-FAN Mode". The manual says:

"Allows you to select the type of cable connected to the CPU fan connector. Set to [PWM] when using a 4-pin CPU fan cable. Set to [DC] when using a 3-pin CPU fan cable." Options [PWM][DC]
"Note: Some CPU fans with a 4-pin cable do not comply with Intel's PWM fan specification. With this type of CPU fan, you cannot reduce the CPU fan speed even if you set the CPU Q-Fan Mode to [PWM]

Does any know precisely what the [DC] mode is? I'm using a Zalman 7700 AlCu heatsink, which is 3-pin. Does the motherboard actually adjust the voltage instead of using PWM?

Also, just to confirm, the chassis fans 1 & 2 would still be PWM? Has anyone had experience with trying "Q-Fan 2"? Is it to be avoided? I was thinking of getting some 120mm Nexus Real Silent fans for the case, and was going to try using them with Q-Fan.
--- Francis

harrigan
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Post by harrigan » Wed Feb 02, 2005 7:23 am

The Nexus fan I have comes with a two-wire/three-pin connector for the motherboard, but it's only for RPM monitoring. It gets its power off the four-pin molex connector. I don't think Q-Fan will be able to control the speed of this type of fan. I haven't actually tried Q-Fan so I could be wrong.

frankgehry
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Q fan

Post by frankgehry » Wed Feb 02, 2005 8:01 am

I have the p5gd2 and use q fan for the cpu cooler only. I connect the other fans to a fan controller. On this board only the cpu fan and one chassis fan can use q - fan. There is one other chassis fan connection plus an rpm sensor from the psu. Its good to use q fan for the cpu fan so if for some reason the cpu starts to heat up the fan will automatically speed up. Its not so important for case fans. Your fans need to have a three pin connector with rpm sensing and i'm pretty sure your psu heeds needs an rmp sensing cable Ask more questions if you like. Let me know what kind of fans you have and how many you need to have q fan for, etc... - FG
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Francis
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Re: Q fan

Post by Francis » Wed Feb 02, 2005 5:28 pm

Thanks for the reply - I did notice the manual mentioning only one chasis fan can be controlled, although you can plug in a second one. In reply to harrigan's post, can you verify that a 3-pin fan such as the Nexus 120mm can be controlled by Q-Fan? (Apparently you can control a 3-pin CPU fan by setting the Q-Fan "CPU fan mode to "DC"" rather than "PWM", but because there's no such setting for the chassis fan, can you control a 3-pin fan?)

By the way, do you have any idea what the difference is between "Q-Fan" and "Q-Fan 2"? Is it assumed the P5GD2 is using PWM? Have you noticed any of the PWM effects on the CPU fan? Have you ever tried using it with one of the chassis fans?

Thanks for any info!
frankgehry wrote:I have the p5gd2 and use q fan for the cpu cooler only. I connect the other fans to a fan controller. On this board only the cpu fan and one chassis fan can use q - fan. There is one other chassis fan connection plus an rpm sensor from the psu. Its good to use q fan for the cpu fan so if for some reason the cpu starts to heat up the fan will automatically speed up. Its not so important for case fans. Your fans need to have a three pin connector with rpm sensing and i'm pretty sure your psu heeds needs an rmp sensing cable Ask more questions if you like. Let me know what kind of fans you have and how many you need to have q fan for, etc... - FG
--- Francis

JanW
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Post by JanW » Wed Feb 02, 2005 6:10 pm

All Nexus fans I have, have three leads going to the 3-pin connector. So they are not for monitoring only, you can actually power the fan off the M/B with the 3-pin connector. FWIW, the Nexus fans are reputed to be some of the best fans in combination with PWM, without the noise this induces in some other fans. Changing the DC voltage (as in a fanmate) does obviously work, too, but I can't comment on what the Asus Q-Fan 2 actually does. Either way, with Nexus fans you should be fine.
Just be aware that from this thread it seems that the orange low speed Yate Loon sleeve bearing fans sold by Yate Loon directly do not necessarily have the +12V line connected at the small 3-pin M/B connector, so you can only use that connector for monitoring, as harrigan hinted.

EDIT: this last statement seems to be wrong, see my post below
Last edited by JanW on Thu Feb 03, 2005 2:00 am, edited 1 time in total.
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frankgehry
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q fan

Post by frankgehry » Wed Feb 02, 2005 7:09 pm

Francis,

Looking at my manual I do see something about q fan 2 but it refers you to chapter 4 and then only mentions q fan from then on. I think they must be the same thing or a misprint. When I set up my bios I set it to DC - I don't see that in my book now, but I remember just following the book defaults. Anyway, I've always just used the 3 pin connector which also supplies power. With the big 4 pin connectors you can plug the fan directly into the power supply. If you set the bios to DC, insert the nexus 3 pin connector into the cpu fan connector you should be fine. My original plan was to use q fan for all of my fans and then I realized that I could just control 2 fans with q fan so I let q fan control the cpu fan and use a fan controller to control the others. I like the front and back fans to stay at a constant rpm, but if the cpu starts getting hot, I would like q fan to control the fan. I just looked up the tech ref and their bios utility is newer than mine. No I don't know exactly what DC means but I think it just means a constant voltage where as PWM provides a pulse which is supposed to allow a fan to run slower because it sends out a pulse of maybe 7 volts, then stops, and then sends another pulse. So if your fan needs six volts to run, but you want it to run at a 5 volt speeds, then sending out a 7 volt pulse will get the fan moving and allow it to coast for a split second and then send another pulse. If you have a zalman you can plug the three pin connector into the cpu fan socket and it should work fine. It will adjust the fan speed using DC. Chassis fan 1 and 2 will use DC. Does your psu have an rpm output? You will be fine with DC, q fan, and nexus. They work great. The p5gd2 is a great board! Seach the forum for a better definition of PWM or make another post. I would like to know for sure too. I'd also like to find out if I can get the new bios utility. - FG

I have some of the yate loons and their three pin connectors can be used for power as well. There are 3 wires - 2 for power and one for rpm sensing.
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Tibors
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Post by Tibors » Wed Feb 02, 2005 7:40 pm

I think (note: not I know) that the 4-pin in the description of Q-fan 2 refers to the new 4-pin standard for CPU fans from Intel. Not the big 4-pin connectors Frank talks about in his last post. This new standard uses a small connector not unlike the small one for 3-pins we are used to. There are four lines instead of three: 12V; ground; PWM signal; RPM signal.

Now just ignore all the references to PWM and DC in the manual and only look at the number of wires.
"Allows you to select the type of cable connected to the CPU fan connector. Set to [PWM] when using a 4-pin CPU fan cable. Set to [DC] when using a 3-pin CPU fan cable." Options [PWM][DC]
With your Zalman 7700-AlCu you need to set it to "DC".
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JanW
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Post by JanW » Thu Feb 03, 2005 1:51 am

I wrote:Just be aware that from this thread it seems that the orange low speed Yate Loon sleeve bearing fans sold by Yate Loon directly do not necessarily have the +12V line connected at the small 3-pin M/B connector...
Actually, I misinterpreted the info on that thread. There seem to be two versions of the Nexus 120mm real silent case fan out there, one with all three wires at the 3-pin M/B connector, and one with only the RPM monitoring connected to that connector, so the fan can only be powered off the molex connectors. In the latter case you might need to do some re-wiring to run the fan off the M/B and have RPM monitoring.
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Michael B
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Post by Michael B » Thu Feb 03, 2005 5:13 am

Francis,

The Asus P5GD2 can support the new Intel PWM format, "CPU Q-FAN Mode". It is designed for the new fans that seperate the fan's coils from the coil control circuits and the RPM sensing circuits. This allows the fan to report back an accurate RPM signal because that circuit is constantly powered.

With the three pin fans the two circuits share the same power and so the RPM circuit turns on and off with the PWM signal resulting in an inaccurate sensing RPM signal, hence the DC mode should be used.


[Edited] "seperate the coil control circuit and the RPM sensing circuits" to "seperate the fan's coils from the coil control circuits and the RPM sensing circuits" - a big change in meaning.
Last edited by Michael B on Sat Feb 05, 2005 4:12 am, edited 1 time in total.
Michael B

Francis
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Post by Francis » Thu Feb 03, 2005 7:33 am

Michael B wrote:Francis,

The Asus P5GD2 can support the new Intel PWM format, "CPU Q-FAN Mode". It is designed for the new fans that seperate the coil control circuit and the RPM sensing circuits. This allows the fan to report back an accurate RPM signal because that circuit is constantly powered.

With the three pin fans the two circuits share the same power and so the RPM circuit turns on and off with the PWM signal resulting in an inaccurate sensing RPM signal, hence the DC mode should be used.
Michael - thanks for the explanation. Does anyone know of case fans that follow Intel's specification? Or should we not expect to see any because it would require some kind of adapter to use in a normal fashion?

What CPU heatsinks have 4-pin fans (besides Intels?)

How innacurrate would you say RPM sensing is in 3-pin fans? Surely it's still accurate enough to be useful?
--- Francis

harrigan
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Post by harrigan » Thu Feb 03, 2005 10:54 am

That's useful information about the two styles of Nexus fans. I purchased my Nexus fan from siliconacoustics.com and it has a two-wire/three-pin connector.

frankgehry, where did you get your three-wire fans?

I've been searching for the new style four-wire fans with no luck. I've seen a few LGA775 coolers, thermaltake makes a couple, with the new style fan. But so far I haven't been able to find separate fans.

** Edited for clarity **

Francis
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Post by Francis » Thu Feb 03, 2005 11:16 am

harrigan wrote:That's useful information about the two styles of Nexus fans. I purchased my Nexus fan from siliconacoustics.com and it has a two-wire/three-pin connector.

frankgehry, where did you get your three-wire fans?

...
Damn! I ordered mine from Silicon Acoustics too! (Haven't received them yet!) I just had to return a power supply to them (incompatibility reasons), they might be pissed if I ended up returning this too! (They're a great company, not trying to give them a hard time!)
--- Francis

frankgehry
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fans

Post by frankgehry » Thu Feb 03, 2005 2:19 pm

I'm pretty sure I bought mine from www.endpcnoise.com. I quess I would just check to make sure you're getting the configuration you want because they might have received a new shipment by now.


Yes, www.endpcnoise.com
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Michael B
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Post by Michael B » Sat Feb 05, 2005 3:49 am

Francis wrote:
Michael - thanks for the explanation. Does anyone know of case fans that follow Intel's specification? Or should we not expect to see any because it would require some kind of adapter to use in a normal fashion?

What CPU heatsinks have 4-pin fans (besides Intels?)

How innacurrate would you say RPM sensing is in 3-pin fans? Surely it's still accurate enough to be useful?

I should have been a bit more clear, RPM sensing with 3-pin fans is only inaccurate when using PWM. Try it! You'll see what I mean. That is why someone invented the new 4-pin fan standard.


Yes, you can just use an adapter to go either way (3-pin fan to 4-pin header or viceversa).

For a 3-pin fan to connect to a 4-pin header you can just use the fan's V+, TACH and GND pins connected to their associated pins on the header. With this method though, the fan speed will not be adjustable but you will get an RPM signal (tach). The other way is to use the DRIVE (PWM) and GND pins on the header connected to the V+ and GND on the fan. With this the fan speed can be controlled but the tach signal will not report correctly (so it is pointless to connect it).

For a 4-pin fan to a 3-pin header you can use the fan's DRIVE (PWM), TACH and GND pins connected to the header's V+, TACH and GND pins (respectively) and will also have to steal a voltage source that is not a PWM to use for the fan's V+ pin (can be the same one that is connected to the header's V+ if not PWM). This will allow the fan to be speed controlled and have RPM functionality.

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