8 Replies Latest reply on Oct 11, 2013 1:32 PM by spearson

    DH77DF startup CPU fan speed?


      I just assembled a new system using a DH77DF motherboard.  Before I installed Win7 x64, I updated the BIOS to the latest version 100 using a USB stick.  No problems, Windows is installed, etc.


      My only question/concern is that when the system is cold started or woken from S3 sleep, the CPU fan runs full speed (really loud) for a few seconds then calms down to a nice quiet ~1040 RPM.  Is that a bug or a feature?  Seriously, the system is nearly silent except at startup, and I would prefer it to be silent all the time.  The CPU fan is stock Intel and seems to be seated properly.  The BIOS says the CPU fan is an Unrecognized Type.  Suggestions?  Is this normal?


      Rest of system is i3-3225, Intel SSD, 8GB RAM, Antec ISK 110 case.

        • 1. Re: DH77DF startup CPU fan speed?

          Mine does the same, and in my experience with Intel motherboards of various types, is normal. Note that you can reduce the minimum fan speed as you wish (I use 20%), but the initial startup speed will remain high.

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          • 2. Re: DH77DF startup CPU fan speed?

            Thanks for the info.  At least I'm not the only one.


            Previously I had a DZ68DB board which I upgraded from a Sandy Bridge to Ivy Bridge processor.  I had been using an aftermarket fan with the SB processor and it was nearly silent all the time.  For the IB processor I tried the stock Intel CPU fan and it roared on startup and after waking from sleep, just like this board.  I took off the Intel fan and put the aftermarket fan back on, and once again it's nearly silent all the time.  At the time I thought I had not properly secured the Intel fan but I guess it's normal behavior.


            My Antec ISK 110 case is so small I don't think any aftermarket fan would fit or I would try one.

            • 3. Re: DH77DF startup CPU fan speed?

              Almost every motherboard (not just ours) has this issue. When it is reset, the SIO device defaults to the fans being on at 100% duty cycle. How fast this is lowered to the operational level is dependent upon two things: (1) how fast the BIOS can get itself initialized and program the SIO and (2) how reactive the fans are to duty cycle change (if they are slow enough, you might not even hear the surge at all). BIOS boot time is a complex issue; there are many things - use of RAID, SSD Caching, etc. - that will slow initialization. In the hardware too, there are lots of variables. 3-wire fans transition at the same rate (typically very fast with our motherboard circuit designs) and this is seen as a negative if the BIOS is slow (you hear the power-on surge). 4-wire fans can vary significantly in how fast they respond to duty cycle changes (its the fan design that determines its rate). Intel's boxed heatsink-fan units are faster than most in their response (though there are some exceptions) - and again this is seen as a negative if the power-on surge is heard. Other heatsink-fan units are much slower and this can hide the surge.


              Some SIO devices include a capability for having the power-on duty cycle be at some lower level. Philosophically, I prefer to have the response be at 100%. Suppose that you have your system running petal to the metal and the heatsink is fully saturated with heat. If the system is suddenly reset (alas, there are buggy device drivers that can cause this) and the fans quickly react by dropping to minimum (or off), then the processor suffers for it. Do it often enough and the processor could suffer degradation. Yea, I am talking a corner case in this example, but, being conservative, I will put up with a few seconds of fan noise to avoid this...


              Best advice I can give you: lower your boot time. Our BIOSs have the Rapid BIOS Boot feature that allows you to speed up boot time. Try playing with this feature; the more time you eliminate, the less time for you to hear the fan surge...



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              • 4. Re: DH77DF startup CPU fan speed?

                Thanks for the inside information.  My aftermarket 4 wire fan evidently responds differently than Intel fans.


                My Intel fan does not run 100% during a warm restart.  It stays quiet.  It only runs 100% during a cold start and after S3 sleep.  I would have expected it to run 100% during a warm restart as well but I suppose not doing so is by design.


                Speaking of rapid BIOS booting, Video Optimization does not work for me:  http://communities.intel.com/thread/31811.

                • 5. Re: DH77DF startup CPU fan speed?

                  The SIO is not reset during a warm restart, so the fans will stay where they are. The reset is only going to occur when the main power rails are dropped...



                  • 6. Re: DH77DF startup CPU fan speed?

                    Thanks again for your help.

                    • 7. Re: DH77DF startup CPU fan speed?

                      I had same situation with fans on DG45FC board when... in BIOS setting was present setup "Detect fans" on fan control page. In case "off" - system will not detect fans and as result - start quietly from any power state.

                      I'm not sure is it present in current BIOS revision for DH77DG, but you can discover it oneself on fan and power management pages and thru Intel® Integrator Toolkit.

                      • 8. Re: DH77DF startup CPU fan speed?



                        The symptoms may appear to be the same, but the situation with your 4 Series board is completely different...


                        In the 4 Series boards, fan control is managed in the chipset. This is a feature called Intel(R) Quiet System Technology (QST). QST included a special feature that tried to get stalled fans to spin again. It worked great, but had a negative side effect. On many of our boards, we used a single fan speed controller to control both the chassis inlet and chassis outlet fans. If one of these fans was present and the other wasn't (or was broken), this feature tried to get this missing/broken fan to start working again. The problem was that the other fan in the pair *was* present and thus you heard it speeding up and slowing down as the feature tried to get the other fan to spin. Not nice to listen to...


                        We added the "Detect Fans" feature to alleviate this issue. By selecting this feature, you were telling QST that, at this particular point in time, all of the fans that are plugged into your board are working properly and any that are not detected (to be spinning) are simply not there. In this case, the fans that are not spinning (not present) will be tracked and the feature that would try to get them working would be disabled. This all sounds good on paper, but there is a problem. The way QST detected which fans were present required that all fans be spun up to 100% for some amount of time. It then checked which fans were not seen to be spinning (we saw 0 RPMs). This is kind of a noisy feature but is only done for a short duration (~6 seconds). The problem is that many folks misunderstood the feature and left it enabled all the time. This results in all of the fans that are present being run at full speed for this amount of time each and every time the system is booted. It also results in fans that are truly failing to end up being ignored (and no alerts generated) potentially permanently.


                        Bottom line, if you have "Detect Fans" enabled all the time, you are creating the problem yourself. Only enable it for a single reboot just after you make a change to the fan configuration of your system (add fans, remove fans, etc.)...