[SOLVED] Bios not recognizing 2 Fans

ioannis2015v

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Dec 12, 2018
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Hello, 2 days ago, I completed my pc build successfully (😂), but I have question here. Firstly, my motherboard has 4 fan headers + 1 cpu fan header and 2 rgb headers (for simple rgb + 1 argb). My case has 2 200mm preinstalled rgb fans and 1 120mm not rgb fan in the rear. I also added 1 more same 200mm rgb in the top, so when I begun building I was thinking that I will populate all fan headers for each fan, and use the rgb splitter which comes with the case (and the rgb controller) to plug 2 fans and then to header 1 and the other top fan straight to the header 2. But, when I started connecting cables, I realized that the rgb splitter was already connected to the front (2) fans with support for one more but also the 2 front fans 3pin cables were connect together with a weird cable (I guess splitter) which also had one more cable running from its edge for support of 1 more fan. Anyway, I simply let it as it was and connected to Sysfan4 header. The top fan straight to sysfan3 and the rear to sysfan1. Later, when I got into Bios sysfan1 and 4 were shown connected and running at a certain rpm while the sysfan4 was disconnected and 0rpm. More weirdly, when I was pressing the button to set all fans of system to full speed, I think they were running faster too. So, what does this happen? Why they are shown 0 rpm and in bios motherboard overview slot 4 shows up as disconnected? Is it due to splitter? I may try to take out the splitter and connect each fan individually to a slot but what are your opinions? One last thing is that when I turn on pc, the top fan makes a a spin, stops and starts again but with no problems, it just doesn't start immediately to spin but I don't think it has any problems.
Sorry for analyzing so much my problem, but I didn't want to miss any point. Thanks in advance...
System specs:
Case: Coolermaster H500
Fans: 3x 200mm rgb fans (CM Mf200r rgb)
1x 120mm black fan (Coolermaster)
Mobo: Msi X470 Gaming Pro Carbon
 
There's a slight misprint above but I believe your problem is that both front 3-pin fans' motors are connected via a Splitter to the mobo SYS_FAN4 header, and yet in BIOS Setup this header shows no fan connected and no speed. Just to confirm, I expect the third male (with pins) output of that Splitter is just like the other two that have fans connected, and it is NOT connected to anything, right?

IMPORTANT point here. There are SOME Splitters that are constructed so you can get power for its fans from EITHER a mobo 4-pin fan header OR a 4-pin Molex power output from the PSU. That is, it has TWO input connectors. IF yours is like that, the Molex one may already be connected to a PSU output. (In that case, the "unused" third connector MAY be a FEMALE one (with holes) that you plugged into the mobo SYS_FAN header, and that is a problem!) A Molex connector is MUCH wider than a fan connector and has space for 4 round pins in a row, but it may actually have only 2 pins installed. IF that is what you have, you must NOT connect BOTH inputs. So in that case you must DISconnect the wider Molex connector from the PSU output, and then plug the female smaller fan connector input to your mobo SYS_FAN4 header. IF you do NOT have this two-input-connector option, ignore this caution.

Now, look at that unused connector closely IF it really is just a smaller MALE fan connector like the other two. Side detail to help understand. Any mobo fan header can deal with the speed signal coming back to it from only ONE fan - more than that gets bad errors. So any Splitter will send back only one fan's speed and ignore others so you will NOT "see" the speeds of those "others" on that Splitter. The most common way to do this is simply to omit Pin #3 on the outputs that are being ignored. So, if the Splitter supplied is a 3-pin model, only ONE of the three male (with pins) output arms will have all three pins. The other two will have only two, usually. IF they supplied a common 4-pin Splitter, then one will have all 4 pins and the other two will be missing #3. This means that, IF the Splitter is to do things right, you MUST have one of the fans plugged into the only output arm that has ALL of its pins. So check that this is so. In fact, I suggest you take the two front fans' connectors one by one and disconnect it from its Splitter arm, then plug it back in a couple of times. Just in case there was a poor connection for Pin #3 on the one that has all of its pins, this may clean the connection and make it work. When it is working properly, you will see the speed of ONE fan shown under SYS_FAN4, but not the other one. This has no impact on ability to control fan speeds.

Now a further refinement of fan header settings. You are using three of the SYS_FAN headers. In the manual for the mobo on p. 39 it says that all four of those are set by default to use the older DC Mode of control. This Mode is necessary for any 3-pin fan, so verify that SYS_FAN4 is set this way - see manual p. 49 for the Advanced menu, choose Hardware Monitor, and select that header. THEN for the two other headers you are using for the top and rear fans, IF the fan is a 3-pin model, also check that it is configured for DC Mode. But IF you are using any 4-pin fan, it is better to configure its header to use the newer PWM Mode. When you have them all set, use Esc to return to the Advanced main manu to choose Save and Exit at top right and there (p. 63) choose to Save Changes and Reboot. Doing this will ensure that, whatever speed control option you choose (Auto, Full Speed, Custom, whatever) the mobo SYS_FAN headers can do that.
 
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ioannis2015v

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Dec 12, 2018
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The RGB connections are separate from the fan control connections, or at least they are on any non-proprietary configuration. I'd disconnect the fans from the integrated header and use the fan headers on the motherboard.
Yes, I connected the 4 pin cables of fans (for rgb) to rgb headers 1 and 2, and the 3 pin (for power) to 3 of 4 fan headers due to the splitter. I will probably try to separate them and use all of fan headers. One last question: I have a bit problem with cooling because in Bios the fans are running a bit slow for silence and there is only a graph I can customise and smart fan option. It cpu fan there is enabled the smart fan but generally the fan is running g too slow (160 of 1500 rpm) and sometimes it spins slower or higher. What are your propositions? I am having 2 cpu fans (1x 140mm on middle and 1x 120mm front, in Bios it shows120mm rpm ) and 3x 200mm and 1x 120mm.
 
There's a slight misprint above but I believe your problem is that both front 3-pin fans' motors are connected via a Splitter to the mobo SYS_FAN4 header, and yet in BIOS Setup this header shows no fan connected and no speed. Just to confirm, I expect the third male (with pins) output of that Splitter is just like the other two that have fans connected, and it is NOT connected to anything, right?

IMPORTANT point here. There are SOME Splitters that are constructed so you can get power for its fans from EITHER a mobo 4-pin fan header OR a 4-pin Molex power output from the PSU. That is, it has TWO input connectors. IF yours is like that, the Molex one may already be connected to a PSU output. (In that case, the "unused" third connector MAY be a FEMALE one (with holes) that you plugged into the mobo SYS_FAN header, and that is a problem!) A Molex connector is MUCH wider than a fan connector and has space for 4 round pins in a row, but it may actually have only 2 pins installed. IF that is what you have, you must NOT connect BOTH inputs. So in that case you must DISconnect the wider Molex connector from the PSU output, and then plug the female smaller fan connector input to your mobo SYS_FAN4 header. IF you do NOT have this two-input-connector option, ignore this caution.

Now, look at that unused connector closely IF it really is just a smaller MALE fan connector like the other two. Side detail to help understand. Any mobo fan header can deal with the speed signal coming back to it from only ONE fan - more than that gets bad errors. So any Splitter will send back only one fan's speed and ignore others so you will NOT "see" the speeds of those "others" on that Splitter. The most common way to do this is simply to omit Pin #3 on the outputs that are being ignored. So, if the Splitter supplied is a 3-pin model, only ONE of the three male (with pins) output arms will have all three pins. The other two will have only two, usually. IF they supplied a common 4-pin Splitter, then one will have all 4 pins and the other two will be missing #3. This means that, IF the Splitter is to do things right, you MUST have one of the fans plugged into the only output arm that has ALL of its pins. So check that this is so. In fact, I suggest you take the two front fans' connectors one by one and disconnect it from its Splitter arm, then plug it back in a couple of times. Just in case there was a poor connection for Pin #3 on the one that has all of its pins, this may clean the connection and make it work. When it is working properly, you will see the speed of ONE fan shown under SYS_FAN4, but not the other one. This has no impact on ability to control fan speeds.

Now a further refinement of fan header settings. You are using three of the SYS_FAN headers. In the manual for the mobo on p. 39 it says that all four of those are set by default to use the older DC Mode of control. This Mode is necessary for any 3-pin fan, so verify that SYS_FAN4 is set this way - see manual p. 49 for the Advanced menu, choose Hardware Monitor, and select that header. THEN for the two other headers you are using for the top and rear fans, IF the fan is a 3-pin model, also check that it is configured for DC Mode. But IF you are using any 4-pin fan, it is better to configure its header to use the newer PWM Mode. When you have them all set, use Esc to return to the Advanced main manu to choose Save and Exit at top right and there (p. 63) choose to Save Changes and Reboot. Doing this will ensure that, whatever speed control option you choose (Auto, Full Speed, Custom, whatever) the mobo SYS_FAN headers can do that.
 
Reactions: ioannis2015v

ioannis2015v

Proper
Dec 12, 2018
160
5
195
1
There's a slight misprint above but I believe your problem is that both front 3-pin fans' motors are connected via a Splitter to the mobo SYS_FAN4 header, and yet in BIOS Setup this header shows no fan connected and no speed. Just to confirm, I expect the third male (with pins) output of that Splitter is just like the other two that have fans connected, and it is NOT connected to anything, right?

IMPORTANT point here. There are SOME Splitters that are constructed so you can get power for its fans from EITHER a mobo 4-pin fan header OR a 4-pin Molex power output from the PSU. That is, it has TWO input connectors. IF yours is like that, the Molex one may already be connected to a PSU output. (In that case, the "unused" third connector MAY be a FEMALE one (with holes) that you plugged into the mobo SYS_FAN header, and that is a problem!) A Molex connector is MUCH wider than a fan connector and has space for 4 round pins in a row, but it may actually have only 2 pins installed. IF that is what you have, you must NOT connect BOTH inputs. So in that case you must DISconnect the wider Molex connector from the PSU output, and then plug the female smaller fan connector input to your mobo SYS_FAN4 header. IF you do NOT have this two-input-connector option, ignore this caution.

Now, look at that unused connector closely IF it really is just a smaller MALE fan connector like the other two. Side detail to help understand. Any mobo fan header can deal with the speed signal coming back to it from only ONE fan - more than that gets bad errors. So any Splitter will send back only one fan's speed and ignore others so you will NOT "see" the speeds of those "others" on that Splitter. The most common way to do this is simply to omit Pin #3 on the outputs that are being ignored. So, if the Splitter supplied is a 3-pin model, only ONE of the three male (with pins) output arms will have all three pins. The other two will have only two, usually. IF they supplied a common 4-pin Splitter, then one will have all 4 pins and the other two will be missing #3. This means that, IF the Splitter is to do things right, you MUST have one of the fans plugged into the only output arm that has ALL of its pins. So check that this is so. In fact, I suggest you take the two front fans' connectors one by one and disconnect it from its Splitter arm, then plug it back in a couple of times. Just in case there was a poor connection for Pin #3 on the one that has all of its pins, this may clean the connection and make it work. When it is working properly, you will see the speed of ONE fan shown under SYS_FAN4, but not the other one. This has no impact on ability to control fan speeds.

Now a further refinement of fan header settings. You are using three of the SYS_FAN headers. In the manual for the mobo on p. 39 it says that all four of those are set by default to use the older DC Mode of control. This Mode is necessary for any 3-pin fan, so verify that SYS_FAN4 is set this way - see manual p. 49 for the Advanced menu, choose Hardware Monitor, and select that header. THEN for the two other headers you are using for the top and rear fans, IF the fan is a 3-pin model, also check that it is configured for DC Mode. But IF you are using any 4-pin fan, it is better to configure its header to use the newer PWM Mode. When you have them all set, use Esc to return to the Advanced main manu to choose Save and Exit at top right and there (p. 63) choose to Save Changes and Reboot. Doing this will ensure that, whatever speed control option you choose (Auto, Full Speed, Custom, whatever) the mobo SYS_FAN headers can do that.
Thank you very very much!!! Responding to some of your questions: firstly I connected this splitter only to the motherboard as the remaining input (had holes to plug sth) I thought it was to plug another fan. So, I think that since I have 1 fan header resting unused, I am gonna unplug them from the splitter and plug each fan to a fan header. Lastly, my problem is that there is no easy option to set for example the fan speeds at standard or performance or silent etc as my old motherboard had. It has only to set all at full speed, at default and customise the graph which I find s bit difficult (and the DC/ PWM/ auto modes). I wish I could simply press a button to make them run at an average speed (not too fast and not too slow). Thanks again for your help, is the best way to customise the graph and if yes, do you know what would be best temps/rpm settings for about 5 dots it has? (1 for 120mm exhaust rear, 2 x 200mm intake front and 1 x 200mm exhaust top).
 

Darkbreeze

Titan
Moderator
Gaahh. If you just connect EACH fan to a motherboard header and change the control setting to DC mode in the BIOS, the problem is done. Over. No more problem. And as mentioned, make sure there is no stupid molex four pins connected to them anywhere.
 
Reactions: ioannis2015v
As you noted, IF you try to set up a "custom fan curve", you need to know exactly what settings are needed, and you do NOT know that; nor do I. As Darkbreeze said, just use the "Default" setting and it will work well. Also as Darkbreeze says, set each fan header to use DC Mode if it has 3-pin fans. PWM Mode is to be used ONLY when the fan on that header is a 4-pin model. And I never trust the "automatic" option for Mode.

Thanks for Best Answer.
 
Reactions: ioannis2015v

ioannis2015v

Proper
Dec 12, 2018
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As you noted, IF you try to set up a "custom fan curve", you need to know exactly what settings are needed, and you do NOT know that; nor do I. As Darkbreeze said, just use the "Default" setting and it will work well. Also as Darkbreeze says, set each fan header to use DC Mode if it has 3-pin fans. PWM Mode is to be used ONLY when the fan on that header is a 4-pin model. And I never trust the "automatic" option for Mode.

Thanks for Best Answer.
Ok thanks, so I will set all case fans to DC and cpu fan to PWM. Cpu fan is already enabled smart control, should I do the same on case fans?
Thanks again...
 

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