I installed a new graphics card earlier today, and afterward my computer's case fans became unusually loud. I checked the BIOS and lowered their fan setting, but nothing changed—even setting them to 0% didn't stop them. Fan-control software also seems unable to change their speed. I removed the graphics card and reset the BIOS, but the fans are still running loudly. The GPU is not currently installed, and the BIOS does not show an RPM reading for the case fans. What should I check?
3 Answers
If the BIOS cannot read the RPM, the fans may not be connected to a controllable motherboard header. Check that the fan plugs are fully seated and that any hub’s SATA power and motherboard signal cables are connected. If the fans use three-pin connectors, set the header to DC/voltage control; four-pin fans should use PWM mode. The wrong mode can leave them running at full speed.
Try stopping or slowing each fan briefly with the system powered off and disconnected, then spin them by hand. If one feels rough, wobbly, or makes grinding noise, its bearing may have failed. Since the problem started around the same time as the hardware change, a loose cable or accidentally disturbed fan controller is also more likely than a BIOS setting problem.
First make sure the noise is actually coming from the case fans and not the graphics card fans. If the GPU has been removed and the noise remains, listen to each case fan individually—one failing bearing can make the whole system seem noisy. Also check whether the fans are connected directly to the motherboard, through a powered hub, or to a separate controller. A hub or controller may ignore BIOS settings.
The GPU is currently out of the computer, so the noise is definitely still coming from the case. The fan wiring is tangled, but I’ll trace each connection and test them one at a time.
Unplugging and reconnecting the cables is worth trying, but make sure you identify the actual motherboard fan header and not just the power connection. Some hubs provide power to every fan but pass no speed-control signal.