Issue with GPU fan speed controller, advice wanted.

[Reaper 392]

Yesterday, after a gaming session, my GTX 970 started making an unusual pulsing sound. Using MSI afterburner and GPUz shows the fan is starting at 1800RPM, accelerating up to 2200RPM and then coasting back down to 1800RPM every second or so. The really unusual thing is that manually setting the fan speed makes the fan audibly much faster, but the fan speed still reads 1800-2200RPM and the pulsing is still audible from the area of the graphics card.

My suspicion is that one of the two fans has a broken speed controller and is the one which both of those programs use to monitor the fan's speed, but that the other fan is perfectly fine (and working overtime during gaming due to the other fan idling).

Does anyone have any advice as to what I can do about this? I have already checked the fan for obstructions and given the PC a reasonably good dusting. I have also posted on the OcUK customer support thread but I appreciate that it is the weekend so a response over there is not very likely until Monday at the earliest.

 

[Danny75]

I can suggest unplugging and re-connecting the GPU power cables. Check the present connectors for any burn/melting signs. Fan/s running at full blast and pulsing sound (from the PCI-E slot overloaded with power draw to compensate) can be a sign of a PCI-E cable failing and not providing power. If your PSU has an extra pair of PCI-E cables, try those too. Just to eliminate that as a possibility.

 

[Reaper 392]

Just as an update, the fan that was pulsing has now stopped completely and the other working fan is going considerably faster to compensate. I can't see the fans to physically check what is happening right now, but the tachometer says the fans are not moving and at least one of the fans is audibly going very quickly.

Thanks for the advice Danny. I had already unplugged and re-plugged the PCIe power cables when dusting off the card. The cables did not look to have any issues but I wasn't paying them much attention. Also, this may not be very relevant now that the bad fan has stopped completely, but 1800-2200RPM is not full blast for these fans, it is actually a little way above idle judging by how loud it was when it was pulsing.