When I turn on PC it says "system fan not detected - press F2 to continue" - New build

SkScotchegg · 30 Jun 2011 at 13:15

Hi there, please can you offer some assistance, this isnt really a big problem, the PC works fine, but if I ever restart or turn off the PC I have to press F2 everytime and just wondered why.

Basically, my old PC died, and I didnt have any cash so I got a HP desktop/tower from comet, took out the mobo/cpu/ram and put them in a brand new "Cooler Master CM-690 II Lite Dominator Case - Black" which I bought from OCUK = http://www.overclockers.co.uk/showproduct.php?prodid=CA-212-CM&groupid=701&catid=7&subcat=29

As you can see the case comes with two huge fans...so I installed the mobo/cpu/ram and put my old gfx and sound cards in aswell as my old PSU...everything went fine and I've been using the PC for past 24 hours.

All the fans on the case are plugged in and turned on, the front one, the back one, the cpu one, everything is fine...but I still get this message, so I found this weird and I took out the fan from the other HP case to see if it made a difference, and it did, the message doesnt appear if I plug in the HP fan, but if I use a coolmaster fan it shows the message.

I tried another fan that is huge too from my old case and it still brought the message up...So I have a total of 4 fans, it will only get rid of the message if I use that one rubbish fan from the HP case...and now you would probably ask me "well, whats the problem, why not just use the HP fan in your case? the more fans the better!!"...well the problem is my new case is amazing and it doesnt have holes for crappy little fans and also the HP fan, the wire coming off of it is like 6 inches which cant reach to the mounted locations of fans anyway in the case because the case is huge...so I cant use the fan even if I wanted to, the wire simply isnt long enough.

So this seems like a really daft situation and yeah this is only a minor problem, not a big problem because I know the case is being cooled and I know everything is fine but I just want to get rid of this message.

So howcome the motherboard will only accept the HP fan as a system fan? Do motherboards know which fans are system fans and which aren't? Does it have some kind of detection? I just thought a fan was a fan? lol Can someone please explain to me why this is happening and how to resolve the situation.

Thanks in advance. :confused:

Moothead2 · 30 Jun 2011 at 13:17

I think it may be because no fan header is plugged into the motherboard.

SkScotchegg · 30 Jun 2011 at 13:20

Moothead2 said:
I think it may be because no fan header is plugged into the motherboard.

I'm not sure what a fan header is, do you mean the brown plug on the end of the wire coming from the fan it self?

I'm defo putting the brown fan plug into the right socket because I made sure I knew where it was when I took the motherboard out the HP case, and there appears to only be one on this mobo...and like I say, if I plug the HP one in, the error message goes away, it detects the HP fan as a system fan, it doesnt for the coolmaster one, and they appear to have the same plugs on the end of each wire?

citizenx13 · 30 Jun 2011 at 13:21

Moothead2 said:
I think it may be because no fan header is plugged into the motherboard.

^ Most likely the case, I am sure you can disable the warning in the BIOS, unfortunately can not advise where so have a look through.

SkScotchegg · 30 Jun 2011 at 13:25

citizenx13 said:
^ Most likely the case, I am sure you can disable the warning in the BIOS, unfortunately can not advise where so have a look through.

Yeah I thought that too, like am sure in the past with my previous PC I could disable "Fan Detection" in the BIOS but when I checked the BIOS it had very limited options and couldn't find any such option.

I'm still curious though as to how a motherboard differentiates between one fan and another, why does it accept one fan as a system fan, and not another?

paradisiac · 30 Jun 2011 at 13:32

SkScotchegg said:
Yeah I thought that too, like am sure in the past with my previous PC I could disable "Fan Detection" in the BIOS but when I checked the BIOS it had very limited options and couldn't find any such option.

I'm still curious though as to how a motherboard differentiates between one fan and another, why does it accept one fan as a system fan, and not another?

might work on speed, maybe the new fan runs at a slower rpm.

citizenx13 · 30 Jun 2011 at 13:33

Pin setup perhaps, the fan you are plugging in have two or three cables? Did you compare the "fan headers" the other fan could have a sensor your fan does not

citizenx13 · 30 Jun 2011 at 13:34

Could also be RPM as mentioned above

citizenx13 · 30 Jun 2011 at 13:36

Google the MB perhaps if the BIOS doe not have the option it is a good old JUMPER that needs attention

SkScotchegg · 30 Jun 2011 at 13:40

Well I just checked, I got 5 fans, I was comparing them to the HP one, and they all have 3 wires coming from the fan to the fan plug it self, and the colours are, red/yellow/black, they all have 3 holes in the brown plug, they seem to have the same voltage, DC12v.

Not sure about detectors tho.

Well do you guys know which fan off OCUK I need to get...my case has 120mm fans and has space for loads more.

Do you think this one will work, it says it has detector?

http://www.overclockers.co.uk/showproduct.php?prodid=FG-045-AK&groupid=701&catid=57&subcat=4

And the fans in my case now have blue LED's so I'd like more blue LED's to go with them.

Thanks again.

paradisiac · 30 Jun 2011 at 13:42

too many fans can be as bad as having no fans at all. so think about positioning and airflow direction before spending out.

SkScotchegg · 30 Jun 2011 at 13:44

paradisiac said:
too many fans can be as bad as having no fans at all. so think about positioning and airflow direction before spending out.

Well I've got 5 here, but at the moment I just got the default 2 that came with the case, so surely one more fan wont hurt? plus I want to get rid of that error message at startup so do you think this one will solve the problem?

http://www.overclockers.co.uk/showproduct.php?prodid=FG-045-AK&groupid=701&catid=57&subcat=4

Akasa AK-274CB-4BLS 120mm Blue LED Fan

This is an ultra quiet 12cm case fan delivering high air volumes with an incredible acoustic performance of only 17.5dB(A). The Cool Blue look is achieved by four hi-bright blue LED complemented with crystal blue frame and blades.

- Application PC Case fan
- Frame dimension 120 x 120 x 25mm
- Fan speed 1200 RPM
- Fan airflow 38.4 CFM
- Fan air pressure 1.17 mm H20
- Fan life expectancy 20000/hrs 25ºC
- Bearing type Sleeve Bearing
- Connector 3-pin with RPM sensor wire
- Voltage rating 12V
- Current rating 0.15 A
- Noise level 17.5 dB(A)
- Product code AK-274CB-4BLS

Cheers.

paradisiac · 30 Jun 2011 at 13:47

SkScotchegg said:
Well I've got 5 here, but at the moment I just got the default 2 that came with the case, so surely one more fan wont hurt? plus I want to get rid of that error message at startup so do you think this one will solve the problem?

http://www.overclockers.co.uk/showproduct.php?prodid=FG-045-AK&groupid=701&catid=57&subcat=4

Cheers.

the error is probably down to you plugging a 3 pin cpu fan into a 4 pin cpu fan header. the 4th pin allows the bios (and other software) to control the speed of the fan (i think). so the onlly way to stop it is by replacing the cpu fan with a 4 pin version or finding a way to disable error messages.

EDIT : seen it says system fan, so might not be the cpu one causing the problem. what headers to you have on the motherboard, all 3 pins or some 4 pin ones?

citizenx13 · 30 Jun 2011 at 13:53

just a thought, there was only one fan in the original (HP) case or perhaps two?

SkScotchegg · 30 Jun 2011 at 13:53

paradisiac said:
the error is probably down to you plugging a 3 pin cpu fan into a 4 pin cpu fan header. the 4th pin allows the bios (and other software) to control the speed of the fan (i think). so the onlly way to stop it is by replacing the cpu fan with a 4 pin version or finding a way to disable error messages.

EDIT : seen it says system fan, so might not be the cpu one causing the problem. what headers to you have on the motherboard, all 3 pins or some 4 pin ones?

Yeah its not the CPU fan, am just talking about the case fan.

When the case fan was plugged into the motherboard in the HP case it was fine, but I couldnt stand to look at the HP case and my friend brought round this brand new coolmaster case which I mentioned to you in the other thread yesterday.

It doesnt make sense to me coz all fans look exactly the same, they all have brown plugs with 3 holes, and the slot that they plug into on the mobo is 3 pins not 4.

SkScotchegg · 30 Jun 2011 at 13:55

citizenx13 said:
just a thought, there was only one fan in the original (HP) case or perhaps two?

Just one, just that rubbish HP one which was sat on the back of the HP case.

paradisiac · 30 Jun 2011 at 14:00

SkScotchegg said:
It doesnt make sense to me coz all fans look exactly the same, they all have brown plugs with 3 holes, and the slot that they plug into on the mobo is 3 pins not 4.

just because they look the same doesnt make them the same. if you have fitted a fan that runs faster/slower than the motherboards settings then that could be the issue. im not saying it is, but it could be. have you plugged the original fan back in to see if the message stops?

citizenx13 · 30 Jun 2011 at 14:01

I suspect the HP fan has some sort of sensor/addition that standard fans do not.
don’t suppose you have a model of the MB? have you tried googling it?

SkScotchegg · 30 Jun 2011 at 14:04

paradisiac said:
just because they look the same doesnt make them the same. if you have fitted a fan that runs faster/slower than the motherboards settings then that could be the issue. im not saying it is, but it could be. have you plugged the original fan back in to see if the message stops?

lol, yeah I said that above mate! haha, yeah it stops when I plug the original fan back in, but my new case doesn't have holes for such a small rubbish fan, and even if it did the fan wire is so short it cant reach the side of the case.

Well because I got it as part of a tower from comit I dont know what it is, usually I would know because I usually buy the parts individually and build the rig from scratch, but circumstances this time prevented me from doing that.

Do you guys know of a program that I can use to see the details of my mobo? I used to have one installed on my old PC, forgot the name, like I used to use CPU-Z and msi afterburner and loads of other programs, forgot the name of the ones that shows you all your hardware tho.

paradisiac · 30 Jun 2011 at 14:06

have you tried with no fans and with fans in just other headers on the motherboard?