Merging two PWM headers into one for a fan setup
Merging two PWM headers into one for a fan setup
Good morning/evening, I need a header splitter, not a fan splitter. My MOBO has a CPU fan header and my GPU has its own. I want a setup that reads both headers and sends the stronger PWM signal to one fan. In my photo, I need the bottom 140mm driven by both CPU and GPU headers. I could just hook the bottom to the GPU, but since I'm air cooling a 5950x, keeping it connected to the CPU makes sense. I'm unsure if a basic splitter would work here because feeding two PWM signals down the same wire could cause issues. If off-the-shelf options don't exist, might a Raspberry Pi PICO help read and drive PWM signals? I already have one running on my screen, so it works.
This approach seems overly complicated for a straightforward solution. Would using the extra fan headers on the motherboard or designing a custom fan curve be easier? I just want to grasp how it works.
It seems you're looking to connect the front intake fan (GPU fan) with the CPU fans. This setup can cause the CPU temperature to rise, triggering the fans to spin up alongside the CPU fans. A fan splitter essentially converts one header into multiple headers, unlike a fan control box. I'm not sure about your specific motherboard model, but on my Gigabyte Z590 Vision D, the fan can be linked to either the CPU or the temperature sensors it came with.
Connect the bottom 140mm to monitor CPU and GPU temperatures. The motherboard should not read GPU temperature data.
It's more complex than it seems. I want the front 140mm intake fan connected to CPU and GPU temperatures, but the motherboard can't read GPU temps. My GPU has a fan header, though I'm not sure if it can be linked back to CPU and GPU temps.
Usually with newer hardware, you can connect a motherboard chassis fan header to track CPU and GPU fans separately. Some software handles both, but it’s generally one or the other—not both at once. The simplest option is using a fan splitter to run multiple fans from one header. Linking both GPU and CPU headers together isn’t possible because it would send conflicting signals, leading to problems. It doesn’t function that way, so your goal isn’t feasible. You can choose to control fans with one or the other, not both.
I manage my own cooling setup and noticed that boosting the fan speeds will balance out the heat from the GPU. It makes me question if the same applies to my setup. Personally, I find it odd that the primary or single X16 slot is placed so near the CPU/cooler, which might not be the best for cooling either part.
I assumed that too. Thinking about a microcontroller project that reads PWM signals and forwards the higher value, I think a fake signal would need to be sent back to each header.
Sadly, without a dedicated GPU temperature sensor, everything relies on software solutions. If you're keeping it simple, JayzTwoCents demonstrated third-party fan controls, though the system still needs to prioritize high-performance settings.