new build custom waterloop, fans, pump, PWM fan hub questions (lol)
new build custom waterloop, fans, pump, PWM fan hub questions (lol)
Hi All,
I'm assembling a PC with a custom waterloop and need some advice on fans and pumps using PWM. I'll begin with the components related to my problem.
I have an MSI z170 gaming M7 motherboard, a NZXT Noctis 450 with a PWM fan hub. The case includes three front fans (two removed, replaced with radiators and two additional fans). There are two radiators—one in front and one on top—each equipped with four-pin fans.
I'm using an EK-XRES 140 DDC 3.2 PWM Elite Pump/Reservoir Combo.
My concern is that the PWM hub only has three pin connections, while my motherboard provides five, four-pin headers, and I can adjust speeds in BIOS for all five. If I connect the four-pin fans to the three-pin headers on the PWM hub (which connects to the CPU fan), they should operate in voltage control mode—assuming 100% speed. Since these are 3000rpm fans, running at full speed would definitely cause excessive noise.
Additionally, the pump uses a four-pin connector, but only two wires come out of it, and it's advertised as PWM-compatible. That’s another point I don’t want to risk by running it at maximum power.
Everything was fine during assembly, but now the fan setup is confusing me a lot. The top fans aren’t even reaching the PWM hub. I’m unsure whether I should opt for a fan controller like the NZXT Grid+ V2 and cable extensions.
Thanks for your help—I’d really appreciate any advice.
PWM generally serves as a BIOS setting that adjusts fan speed according to the temperature of the CPU die. It usually involves a change in voltage, either increasing or decreasing it, depending on the thermal load. You don't always have precise knowledge of the RPM the fan can handle.
I believe you're focusing too much on the PWM aspect of the pump problem. Many people who use watercoolers don't even use the PWM function on pumps (including me). Running it at full power is completely acceptable and you'll notice it's almost silent, and it won't cause any major issues either.
Most users in this scenario opt for a fan controller instead of relying solely on PWM for multiple radiator fans. You can purchase high-end controllers with LCD or digital readouts, or simpler ones that just have a resistor dial.
I understand your suggestion, and it's a reasonable approach – consolidating the PWM control into one header ensures all fans receive identical RPM signals. You might want to check Amazon or eBay for affordable fan extension cables; they should be quite inexpensive.
Thanks for your response. Here’s a revised version:
I have a suggestion that could help,
The PWM hub should connect to the CPUFAN header for optimal performance, and it includes a 1 4-pin port for a CPU cooler.
Plan:
PWM hub → CPUFAN1 (mobo)
Pump → 4-pin CPU cooler port on PWM hub
2, 3 pin case fans → PWM hub
2 radial fans → Y splitter → CPUFAN2 header
2 radial fans → Y splitter → system fan header
This way I avoid purchasing a controller or additional modules.
Do you know if the PWM function adjusts to temperature changes? Or is it typically set at a fixed speed?
PWM generally serves as a BIOS setting to adjust fan speed according to the temperature of the CPU die. It usually involves a change in voltage, either increasing or decreasing it, depending on the heat level. This method doesn't rely on knowing the exact RPM the fan can handle.