Connecting CPU fan to chasis fan pins instead of CPU fan pins.

[laukinis60]

Hello everyone, I have used dell optiplex 7010 laying around with i5-3470 and thought I could put it to good use and make it a secondary gaming pc.

I've replaced its case (from SFF to a bigger one). Also have a better PSU and gonna buy used GPU, because right now it has none.
While chaning cases I thought I'll try to change CPU cooler from default which was already in dell to an intel stock which I had laying around and collecting dust.
Problem was that fan pins where covered with plastic so intel would not fit in there..
I've removed plastic around pins (mistake?) and tried connecting intel's cooler. It did not work straight away. After playing around for a bit with how to connect it seemed to work, but after a while it just stopped (maybe I broke it.. have not tested it on different machine).

The issue is that now when I try to connect default cooler to those pins (CPU_FAN) it always spins at 4,5k rpms. I know it's not a fan's problem because I've also tried to connect case fan to it (came with same dell and has same connectors) and it too spins at 4,000+ rpm.

I came with a solution I've connected CPU fan into case fan pins and it spins at around 1k rpm.

My question would be is it possilbe to leave it like that? (speed fan shows normal temperatures)
Another question would be is it possible to fix CPU_FAN slot? If it is really faulty.

p.s dell's bios does not have fan control options to change it speed. It only has one option to make it run at full speed which is disabled.

Going to watch this thread. I hope someone can help me or suggest something. If not - have a great laugh and a great day

 

[CountMike]

If temps are normal, why not ? Many MBs wouldn't let you start computer without CPU_fan connected but apparently this one does. Only downfall is that you may not get a warning if the fan stops which is usually reserved for CPU_Fan connection.

 

[laukinis60]

If temps are normal, why not ? Many MBs wouldn't let you start computer without CPU_fan connected but apparently this one does. Only downfall is that you may not get a warning if the fan stops which is usually reserved for CPU_Fan connection.

It shows warning that there is no CPU_FAN but lets to continue by pressing F1 😛

Hmm any thoughts about those CPU_FAN pins? Maybe I can do something about them? Or resoldering is the solution?

 

[CountMike]

https://allpinouts.org/pinouts/connectors/motherboards/motherboard-cpu-4-pin-fan/

 

[laukinis60]

https://allpinouts.org/pinouts/connectors/motherboards/motherboard-cpu-4-pin-fan/

Thank you for the info. Probably gonna pick your answers as a solution but lets wait some more ) maybe other people will add something usefull or new 😛P

In mean time this thread gives more insights with similar situation:
http://www.tomshardware.co.uk/answers/id-2965257/cpu-heatsink-pin-plug-doesnt-fit-motherboard.html

 

[CountMike]

Check voltages on the MB side of connector, two end ones on one side should give 12vDC and any fan should work of just those two albeit at full speed. If there's no voltage than something is blown on the MB.

 

[william p]

If the PWM circuit isn't working then the fan will run full speed in fail safe mode. The PWM wire is the 4th Blue wire. It works by sending a % square wave signal on the ground circuit. The CPU PWM reads CPU temperature and adjust speed from that. The case fan read ambient temperature, or internal temperature and responds to that. My guess is you blew out the MB CPU PWM circuit. One solution would be to use a tower cooler and get a Thermal Speed Control fan. These were used in pre PWM computers. The reason for the tower cooler is it must be mounted as pull through to sense the heat from the CPU load. They use standard 3 wires +12,Grd, RPM.
Here's a video showing one of these fans.
https://www.youtube.com/watch?v=AVovy7UWDQ0
Since computers have been PWN for over 10 years you might have to go back to Pentium 4 era to find one.
The fan fail error in the BIOS needs to be cleared manually. SETUP/Maintenance/ Error Messages, or SYSLOG.

 

[william p]

The old Dell Dimension 4600 used these type of fans. 92x32mm size. Be warned PWM fans can run down to 25-30% speed at idle, The Thermistor fans idle at about 40-50%. So expect 2k fan speed and up.

 

[laukinis60]

Also I've noticed that jumper from PSWD pins is missing. Can it have impact on system?

UPDATE

I've managed to hook intel's CPU fan in a working condition (only because you taught me about cables)
It seems to be running at lower speeds than dells and is a lot quieter. So probably it can't reach speed of 4k rpms?

Either way right now I'm leaving CPU fan connected to case fan pins if any stability problems occur I'll change the coolers.

Thank you everyone.