iMac CPU Fan 0rpm but full speed...

snerkone

macrumors newbie
Original poster
Aug 18, 2014
4
0
Leuven, Belgium
Hi guys,

I've recently bought a secondhand iMac 27" 2010 (old, yes I know) but the machine performs still at its best!
It's a quadcore i7 2,93GHz with a 1gb graphics card.

Now, I replaced the hdd, since it was one of the faulty Seagate hdd's, with a 1 TB Western Digital Caviar Black. I'm more then happy with this drive (gets read & write around 160mb/sec).
When I replaced the drive, I must have pulled to hard at something because immediately when I push the power button, the CPU fan starts spinning at full speed. I triple checked if everything was connected and there seems nothing wrong.

I know that when you replace a hdd, the temp sensor disappears and your HDD-fan also spins at full speed, but this I've managed to fix through some free software. The CPU-fan still reads 0 rpm.

I've did some research and found someone on macrumors-forum who has put a resistor on the CPU-fan connector, this isn't a full fix though, it just makes your CPU-fan run slower. So when a higher rpm is needed, this isn't possible.

I couldn't find the link but somewhere else I've found someone who saw that when he unplugged the Power button connector, a tiny resistor had come off. Check attachment: the orange circle marks the spot (sorry for the other arrows)
I've brought my beloved iMac to a computer specialist, let the resistor solder back on (new one, same kind) but without succes.

Anyone had some experience with this and/or has a solution rather than buying a new logic board or iMac?
Help is appreciated!
 

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aathes

macrumors newbie
Mar 4, 2017
2
0
Did you figure out what was wrong with iMac finally? I'm having the exact same problem with mine, except no resistor is missing from the board...

Thanks!

Matt
Hi guys,

I've recently bought a secondhand iMac 27" 2010 (old, yes I know) but the machine performs still at its best!
It's a quadcore i7 2,93GHz with a 1gb graphics card.

Now, I replaced the hdd, since it was one of the faulty Seagate hdd's, with a 1 TB Western Digital Caviar Black. I'm more then happy with this drive (gets read & write around 160mb/sec).
When I replaced the drive, I must have pulled to hard at something because immediately when I push the power button, the CPU fan starts spinning at full speed. I triple checked if everything was connected and there seems nothing wrong.

I know that when you replace a hdd, the temp sensor disappears and your HDD-fan also spins at full speed, but this I've managed to fix through some free software. The CPU-fan still reads 0 rpm.

I've did some research and found someone on macrumors-forum who has put a resistor on the CPU-fan connector, this isn't a full fix though, it just makes your CPU-fan run slower. So when a higher rpm is needed, this isn't possible.

I couldn't find the link but somewhere else I've found someone who saw that when he unplugged the Power button connector, a tiny resistor had come off. Check attachment: the orange circle marks the spot (sorry for the other arrows)
I've brought my beloved iMac to a computer specialist, let the resistor solder back on (new one, same kind) but without succes.

Anyone had some experience with this and/or has a solution rather than buying a new logic board or iMac?
Help is appreciated!
 

nambuccaheadsau

macrumors 68000
Oct 19, 2007
1,741
409
Nambucca Heads Australia
When replacing the hard drive in your iMac, it is necessary to replace the hard with the identical model and then re-connect the heat sensor cable, which is pretty fragile after that many years service. That Jumbo down the runway is so typical.

OWC have brought out a kit to overcome this so you can use any brand of drive, including SSD's.


https://eshop.macsales.com/item/OWC/DIDIMACHDD09/
 
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aathes

macrumors newbie
Mar 4, 2017
2
0
Hard Drive is the original and was not replaced it's the CPU fan that's blowing on full throttle...