Originally posted by: Buz2b
Originally posted by: L00PY
I'm in disagreement with Buzz2b. The specs strongly suggest you'll be fine using two of those fans off a mobo header. Just run a single tach wire to the mobo header.
If that is the case, then why don't MB manufacturers spec out the fans (plural) that can be used on one header. And why aren't there MB header fan splitters for this purpose, as common as there are with ones for the PSU. "Strongly suggest" is the same as saying "might". Yeah, it "might" work. But yeah, it "might" blow out a header on the MB. Silly thing to try when there are multiple other remedies and/or methods to accomplish the same thing with no worries about MB.
Don't be silly. MB manufacturers can't possibly list all possible combinations of fans. They rarely give actual header information. When they list max amp draw, that's the max amp draw. If you'd like to explain how two fans combined drawing less than 1 Amp will blow out a header, when one fan drawing more than 1 Amp won't, I'd love to hear it.
Running off the mobo header lets you automatically adjust fan speeds depending on temperature.
And........? This much is already known. The same thing can be manually adjusted via a simple fan controller.
Manual does not equal automatic. If I'm out of the room and mobo temperature readings go up, fans speeds will automatically increase in my rig. How can a manually adjustable controller do that? If I'm watching a TV in fullscreen mode or in the middle of an intense fullscreen gaming session and the temperature rises, fan speeds will automatically increase in my rig. With a manual controller, you'll have to 1) notice that temps increased, and 2) turn the knob. Do you always insist upon buying something extra to do something that's already built into the mobo?
I have no idea what RPMs the fans are running at (they're 80mm Panaflo L1A's without RPM tach), but that doesn't matter to me. All that matters is the temperature, noise, and automatic adjustment.
In this case you would want to add MB survival. Look, I'm not saying that without a doubt, the MB would be damaged. It might well survive. However, this is a silly damned thing to try when there are other, safer ways to do the same thing. Have you ever read a thread titled, "Look at the two/three panaflo's I have hooked up to one of my MB headers? No? You ever wonder why?. Even if he did get them to "run", running two tach wires to the single header will only provide garbage as a readout; thus eliminating the one thing he wants to do, gain control over the fan speeds.
Tach wires don't control speeds, they just report them. If he wants to gain control over fan speeds, he needs to control the voltage powering the fans. To answer one of his original questions, all the tach wire does is carry a voltage blip when the fan makes one rotation. The mobo counts the blips and reports that number. (Of course there are different fans, different multipliers, and different divisors to those blips, but that's the gist of it.) It's possible that you might even be able to pass both tachs to the mobo header, double the divisor, and have an average fan speed reported. This gains you very little when using the same model fan though and probably shouldn't be done.
Again, please explain how using a
properly wired splitter to power two 0.3A fans will draw more than .74A his headers can support? It should do exactly what he's looking to do.
I'm as certain that that setup won't blow a header as you must be that adding an additional piece of hardware won't introduce a short, will be properly wired and grounded, will mount in his rig, and will be able to support any fans he throws at it.
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