Originally Posted by grifftech
Hopefully it's OK to ask questions in here. I am going to be doing my first WC rig and getting everything sorted is quite a task
Anyone know of or use a Z87 mobo that has more than 1 PWM fan header besides the CPU_FAN. I will be controlling my Swiftech PWM pump with the CPU_FAN and would love to be able to have my fans throttle in sync with the pump depending on CPU load.
Are there any good PWM LED radiator fans out there?
I will stop there, don't want to do a brain dump in one post.
Originally Posted by lowfat
With my Z87X-UD5H I have 5. Withe the Gigabyte software I can control the speed of everyone of them even if they aren't PWM fans.
While you may be able to control the speed of fans connected to the sysfan and cpu-opt headers, they are clearly not PWM headers in the same way that we refer to a CPU fan header as PWM, meaning for a designated 4 pin fan, with the 4th pin being a 5V duty cycle modulated control signal.
Pages 26 & 27 of the manual clearly show that the 4th pin is a fixed 5V pin, (VCC)
The normal +12V second pin is used for speed control, either by controlling voltage, or pulse width modulating the 12V supply.
If you were to connect a 4 wire PWM fan to one of these headers, it would appear to work, but only because the VCC pin would be telling the fan to run at full speed, while the power delivery from the 2nd pin would be the actual controlling factor.
For fans, it really wouldn't make a crap load of difference whether 3 pin or 4, as either fan will change speed,
For controlling a PWM pump, that gets its power from a molex, it won't do squat. . . .
And powering the pump from the header, while it would likely work at first, would ultimately fry the header, as they are not typically designed for that much load.
To grifftech who asked the question, . . . yes, with a PWM pump on the CPU fan header, it will throttle based on CPU temp, though that doesn't really gain you anything more than annoying variations in noise, . . . . and fans, whether they are 3 pin or 4 pin, can be controlled from the other headers.
There's actually no reason to spend the extra cost for real 4 wire PWM fans either, if you plan to run them from sys fan headers anyway.
If you're using the Swiftech 35X, beware that the published graph is typically crap, it stays at min speed until about 17%, and then is fully maxed out slightly before 50% PWM.
If you're going to use the CPU temp to control the speed anyway, use the info I posted to set up your curve.
In reality, you're really just better off setting the pump at a fixed speed that gives a nominal 1 to 1.5 GPM flow rate and varying just the fan speeds to control temps.
Unfortunately, there's yet another downfall to the plan to run the pump from the CPU header and the fans from the sysfan headers, in that the mobo headers seldom have the current sourcing capacity to run the number of fans on a water cooling setup.
The only work around for that would be to use real PWM fans, power them from the PSU, and use just the PWM signal from the CPU header . . . . and then you'd still need a way to have a real PWM signal for your pump.
Just stuff to think about as you plan . . .
DarleneEdited by IT Diva - 10/5/13 at 7:36pm