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Trouble with PWM control on chassis fan headers w/ PWM splitter?

post #1 of 53
Thread Starter 
I've an Asus M5A97 R2.0 motherboard which has three 4 pin chassis headers and one 4 pin cpu cooler header. These headers are clearly PWM/RPM/12v/ground as shown in the owners manual. I purchased four Xigmatek XAF-F1255 120mm 4-pin pwm fans for CPU cooler and Chassis front panel and rear exhaust. I also got two Xigmatek XAF-1454 140mm 4-pin pwm fans for chassis bottom inlet and top exhaust. I used two Rosewill RCW-FPS-401 3-way pwm splitters. I wired the three 120mm chassis fans on fan header 1, the 120mm cpu fan on cpu fan header, and the 140mm chassis fans on fan header 2. The splitters are hooked up correctly - one fan is plugged into the "cpu fan" lead with 4 pins. The 2 wire pwm and rpm feedback lead is plugged into the mobo, and naturally the molex connector is attached to PSU molex. with this arrangement the fans on the splitters run at 100% no matter what. If I use one of the splitters with the CPU header, all fans on that splitter are speed controlled as they should be. I checked bios and FanXpert to try to find a way to select voltage control or pwm control but could not. I even downloaded SpeedFan to try it. When I plug the fans directly to the mobo chassis fan headers, the speed is controlled but I'm not sure if it's varied voltage or pwm. While looking into it last night I also found out that the Asus minimum speed on chassis fans on manual mode in the bios is 60% which seems to be a standard or some sort, which is really not low enough at all. For now I have the CPU and two front fans on the CPU header via one of the splitters and the rear fan on header 1, top fan on header 2 and the bottom fan is on the splitter via header 3 but it's on at 100%.. I'd just plug it directly but the cable is too short.

So, I guess I have a couple of options... A, get this issue resolved and have it run the way I originally intended, B, simply purchase an extension or make one out of the splitter to get the bottom chassis fan on the header and have the fronts cpu speed based and the others chassis speed based, or gang them all on the cpu speed signal to make use of the lower 20% setting. I will say this is a huge improvement over the stock 3 fans... motherboard temps down by about 10c, cpu down almost 10c while playing bf3 (my "under load") and GPU is down almost 10c while playing as well.

Anyone have any ideas or suggestions?

LL
post #2 of 53
*Plug the second PWM splitter 2pin fan plug into splitter that's working. This will give you 5 PWM controlled sockets. I've ran 9 fans of of one PWM motherboard socket. You can run 5 no problem.

*Contact Asus support or go onto Asus forum and ask them what the problem is. Many motherboards have 4 pin fan sockets but 4th pin is "reserved" and not PWM. But your manual does say all four are PWM. Maybe they really are not. wink.gif
post #3 of 53
Thread Starter 
oh man, I didn't even think of that - and it's so simple! I did really want the fans on separate headers because they operate at different RPMs and I wanted to see the values...
post #4 of 53
Thread Starter 
Well I'm still one pwm lead short because I'm using one of the fan leads to plug the 2nd pwm splitter's mobo lead into, so I've one fan plugged into a chassis fan header. I guess I should head over to the asus forum and try to see what's what.
post #5 of 53
You can use the rpm signal from any of them to whatever sensor you want. wink.gif

Cannibalize an old 3 pin fan splitter for the plug and rpm lead.. remove the other two leads to use on a couple of cannibalized fan plugs for dead fans.
Insert pin into rpm hole in splitter socket.
Plug 3pin plug with rpm into mobo header.

Plug, wire and pin from old splitter

Edited by doyll - 1/26/13 at 10:11am
post #6 of 53
You can always add another PWM splitter. wink.gif

If my GPU was a heat monster I would make sure it had PWM controlled fans and run a case fan or two using it's PWM signal. Working GPU hard and fans supplying GPU cooling air rev up with GPU fans. biggrin.gif

Only problem is GPU use a miniature PWM plug/socket and I have no idea where to get them from. frown.gif
post #7 of 53
If your motherboard has fan headers like this sister model then only cpu fan header works with PWM control, others may work with voltage control


Edited by mm67 - 1/26/13 at 12:14pm
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Shinobi XL
(11 items)
 
Cosmos 2
(9 items)
 
Raven RV03
(8 items)
 
CPUMotherboardGraphicsRAM
Intel Core i7-3770K Asrock Z77 OC Formula XFX Radeon HD 7870 XT Kingston HyperX Predator 2400 MHz 2*4 GB 
CoolingCoolingOSPower
EK Supreme HF EK-VGA Supreme HF Windows 7 Ultimate  Silverstone 1200W Strider Gold Evolution v2.0 
Case
Cooler Master Cosmos II 
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post #8 of 53
Thread Starter 
Not according to the manual for the R2.0 - though it is interesting nomenclature. ground, power, "in" ?? and PWM.

LL
Edited by Gavush - 1/26/13 at 3:39pm
post #9 of 53
Looks to me like a question for Asus to answer. Hopefully they can do that. wink.gif
post #10 of 53
Thread Starter 
I got this from a guy on the asus forum but it didn't seem to work:
Quote:
You should launch Fan Xpert, click fan name, and choose the Disable setting for the chassis fans. Most people don't use PWN chassis fans, so they can use Fan Xpert instead.

The PWN speed setting will be controlled by Q-fan control. There are two BIOS default settings:
1) CPU [Enabled]
2) Chassis [Disabled]

Unless you Enable the Chassis Q-Fan Control, PWN won't work. The standard profile use the case temp to adjust speeds. There are other profiles - silent, etc.

I tried it but didn't have any change in fan RPM when I pull the header off the motherboard indicating no pwm signal. I was going to bring home a voltmeter from work and see if it's varying the voltage at different speeds.
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