Looking for info on fan speed control

I'll be building a computer for the first time 5-6 months from now. I'm having no trouble researching all the important stuff, but I've come across a (relatively) minor issue that I can't seem to find much about. The lack of importance and lack of information are probably related, but I'd still like to know all I can.

I understand that system fans can be controlled by the motherboard. I'd like to do that if possible, as it seems like a more elegant solution then simply leaving them all on max all the time.

I'll post a few of the relevant parts that I've been looking at. Just for context though, as there is no way of knowing what my actual build will be 5 months down the line.

CM 690

GIGABYTE GA-MA790FXT

CORSAIR CMPSU-650TX


Ok, now some questions to give an idea of the issues I'm looking at.


If I power the three fans on the CM690 directly from the power supply, will they simply run full speed all the time? How loud would they be in that event?

From reading, it looks the the CM690 comes installed with 3pin fans. My understanding is that the fourth pin on some fans is for speed control, but that 3pin fans can typically be controlled anyway. Is that correct?


That motherboard, like most of them I've seen, doesn't have 3 system fan headers. It is listed as having one 4pin and one 3pin.

If I plug one of the 3pin fans on the CM690 into a 3pin header, would that fan have its speed controlled though the motherboard?

Can I plug a 3pin fan into a 4pin header, and would it likely be controlled?

I've actually seen people say that you should NEVER EVER plug a single system fan into a header specifically designed for system fans, for fear of blowing the motherboard. You see a lot of people online proving how tech savy they are by repeating bad information they have heard from other people trying to prove how tech savy they are, and that is what those warnings most look like to me. I'm not an expert though, so I could be wrong.

The warnings to never connect two fans to one header using a splitter strike me as a lot more credible. How great a risk would that be? Obviously it would have to be near zero to be worth it. If there is very little risk, would two fans on one header both be controlled?

I've also noticed that a lot of motherboards have headers for a power fan and northbridge fan. Are either of those typically used? If not, could you connect a regular system fan to one and control it through the motherboard?


This is all the sort of stuff that I have learned absolutely nothing about from doing upgrades over the years. I realize it's not the most important issue around, but I figure someone who has built a few machines might know enough to help me out.
9 answers Last reply
More about looking info speed control
  1. Quote:
    If I power the three fans on the CM690 directly from the power supply, will they simply run full speed all the time? How loud would they be in that event?


    A bit. If you want quiet fans that still push a lot of air, buy Scythe, Noctua, or Yate Loon. You can always install better fans on a good case such as the CM 690 or Antec 300.

    Stop the worries. Just get a fan controller. They come in all sorts of styles and add to the look of your case. They give you a level of control that you can't get through the MB.

    http://www.newegg.com/Product/Product.aspx?Item=N82E16811998038

    http://www.newegg.com/Product/Product.aspx?Item=N82E16811999171

    http://www.newegg.com/Store/SubCategory.aspx?SubCategory=11&name=Controller-Panels
  2. Proximon said:
    Quote:
    If I power the three fans on the CM690 directly from the power supply, will they simply run full speed all the time? How loud would they be in that event?


    A bit. If you want quiet fans that still push a lot of air, buy Scythe, Noctua, or Yate Loon. You can always install better fans on a good case such as the CM 690 or Antec 300.

    Stop the worries. Just get a fan controller. They come in all sorts of styles and add to the look of your case. They give you a level of control that you can't get through the MB.

    http://www.newegg.com/Product/Product.aspx?Item=N82E16811998038

    http://www.newegg.com/Product/Product.aspx?Item=N82E16811999171

    http://www.newegg.com/Store/SubCategory.aspx?SubCategory=11&name=Controller-Panels



    Thanks for the response. I recognized your name from when I read your parts guide. It was extremely helpful.

    I think I'd be more likely to replace the fans then put in a fan controller, although I'd just as soon not have to do either. Whether they add to the case's looks or not is a matter of taste, and I think I propably come down on the side of "not". I certainly haven't seen them all though, and it's not like I'll be using all the front bays.

    I think it's fair to say I'm not so much worried as frustrated. I'm used to being able to find answers to questions online, usualy without having to bug people for help on forums. I realize that this is a pretty trivial subject, it just seems odd to me that I have been able to learn almost nothing.

    It just kind of bothers me that I can't seem to find any good information to base a decision around. For example, I'd probably rather run just two fans properly controlled then run three at full all the time. I realize that is blasphemy around here, but I'm not looking to set any overclocking records. The computer will be in a fairly cool room, and the benchmarks I've seen have led me to believe that fans one and two make more of a difference then the third.

    Having said that, I know it doesn't matter all that much. It's not the end of the world if I can't find out what I want to know. Annoying, but not the end of the world.
  3. Proximon said:



    Thanks a lot. That Intel link answered one of my main questions. I guess the only real question I have left is whether a 3pin header labeled as being for a type of fan other then system fan would be usable. If that is not doable then motherboard control is out, leaving running all three at full power as my only free option. I guess that is not a huge deal though, and fan controllers aren't the biggest budget-busters in the world.

    Again, I really do appreciate you taking the time to post good information on something that can't be described as the worlds most important topic.
  4. Sorry I couldn't be verbose earlier... I was posting on the fly.

    If you have a fan header that is for, let's say, the northbridge, that header will respond to the temperature of the NB. Not a very good way to keep the entire system cool. Your video card might be hot while your NB remains relatively cool.

    No, the only fan I want my motherboard controlling is my CPU cooler. My 4 case fans are all running at half speed, very quietly. If it gets hot I have the ability to reach over and turn the knobs to increase the speeds.
  5. There is a budget option to controlling fan noise

    http://www.techpowerup.com/articles/other/137
  6. Quote:
    Sorry I couldn't be verbose earlier... I was posting on the fly.


    No need to apologize; your previous post was actually very helpful. I'd pretty much figured out the bit about the northbridge in the meantime, but the confirmation is certainly helpful. Also, I'll have to remember verbose in the future. I can use that instead of long-winded to describe my next post.

    The two DIY electronics links look like painfuly simple projects for anyone who does that sort of thing. I don't, and I'd just as soon not complicate my first computer build by trying to learn it at the same time.

    I'll probably just end up grabbing a fan controller. I liked the idea of all the fans simply turning up or down automagically based on heat. Having to turn a couple of dials won't kill me though, especially since three fairly large fans on medium should be plenty 95% of the time.

    I think I pretty much know all I need to on the subject now. To sum up: we could probably just delete everything after Proximon's first reply without losing much.

    I'm still happier knowing the specifics. It was nice of people to take the time to feed my curiousity.
  7. You could get a controller that will do the auto thing too you know :)

    I own this one:
    http://www.newegg.com/Product/Product.aspx?Item=N82E16811999046
    Which I use.

    And a Silverstone controller much like this one:
    http://www.newegg.com/Product/Product.aspx?Item=N82E16811998057
    that I don't bother with. I can't stand the extra wires running around the case for the temp sensors, and every time I power up the comp the alarm in the unit beeps rather annoyingly, apparently as a test.

    You don't have to use either type though. Many variable fans come with controllers built in. There are simple ones like these:
    http://www.newegg.com/Product/Product.aspx?Item=N82E16835209005
    That have an in-line switch to control fan speed. Not much good for changing speeds as you have to open the case up.

    Then there are these kind:
    http://www.newegg.com/Product/Product.aspx?Item=N82E16811999122
    that have a controller that is installed in the back of the case, in an expansion bay.
  8. Good grief you're helpful.

    Quote:
    Many variable fans come with controllers built in. There are simple ones like these:
    http://www.newegg.com/Product/Prod [...] 6835209005
    That have an in-line switch to control fan speed. Not much good for changing speeds as you have to open the case up.

    I was aware of that from previous research. I figured I'd be better off just buying fans that run quiet at full speed then buying ones that I'd have to open the case to adjust.


    Quote:
    Then there are these kind:
    http://www.newegg.com/Product/Prod [...] 6811999122
    that have a controller that is installed in the back of the case, in an expansion bay.

    Those actually look pretty cool. I'm thinking though that replacing the three cm690 fans with three of those would cost at least as much as a fan controller, and probably be a bit more hassle. I'd probably get better fans out of the deal though, so it is something to consider. I've mostly gotten over my issues with the aesthetics of a front fan controller.


    Quote:
    You could get a controller that will do the auto thing too you know :)

    I discovered that looking through fan controllers on Newegg earlier today. The only one I saw that gave any kind of manual control along with automatic control was stupidly expensive, took up two drive bays, and had more bells and whistles then I really need. Not to mention using batteries.

    After thinking about it, I've basically decided that just manual control is probably more pratical then just automatic control. Having both would be nice, but not nice enough for the level of hassle it would probably take. Just manual will let me turn it down enough to be quite for something like music, then back up to help dissipate the added video card and cpu heat from something like gaming. Practicality wins.

    I was mostly deciding between two controllers similar to the ones you linked. My main concern with a slightly fancier one, other then cost, was that the sceen might annoy the hell out of me when I listen to music in the dark. If they are that much of a hassle though that pretty much seals it for simple and cheap.


    I think I was even more "verbose" then normal, so apologies to anyone who actually read all of that. I had some noise in the background distracting me.

    At this point I have three of four options better then simply letting the fans run full power all the time, so I think I'm in pretty good shape. I'll see what everything costs in a few months and make a RIDICULOUSLY well informed decision then.
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