Note: this has been updated for the corrected mobo model in OP's later post of Mar 5/24.
There's a better way for you with the mobo headers you have. First I'll explain why, then how.
Before going further, download the TWO manuals for that mobo, one for the mobo layout and structure
https://download.gigabyte.com/FileL...1202_e.pdf?v=63d16298b9e15d4bbeeaa9c4b713e875
The other is for making adjustments in BIOS Setup
https://download.gigabyte.com/FileL...bios_e.pdf?v=aceb9fb3f69cc73ea6b2fddd6a6f34ed
All mobos have two different classes of fan headers. They differ on which TEMPERATURE sensor each uses. One group is for cooling the CPU chip and uses only the sensor inside the CPU chip itself. You have ONE such header: CPU_FAN. The other group are SYS_FAN headers normally used for case ventilation fans, and these give you an option which temp sensor to use. While you can choose the one inside the CPU chip for special functions, normally you choose the sensor on the mobo for these. Your mobo has three of these.
All fan headers have three functions: provide power to the device attached, control its speed, and monitor that speed signal for failure. All fans generate a speed signal consisting of pulses and send that back to the host header on Pin #3. The header can count those and display the fan speed, but it does NOT use that value for its speed control functions. Actually, speed is just manipulated by the header to achieve a TEMPERATURE target at the sensor chosen. But the header DOES use the speed signal to monitor for NO signal, indicating failure. If failure is detected most headers will pop a warning onto your screen so you know it needs fixing. But the CPU_FAN header usually will take more drastic action. If no fan speed is detected there, you get a prompt warning but very soon it will simply shut down your system without waiting for the sensor inside the CPU chip to show temps too high. This is to prevent very rapid overheating with no CPU cooling that might damage the CPU permanently. Such CPU_FAN headers often will not allow you to start up if there is no speed signal at that header.
So, speed control is important for all fans and a pump, but failure detection is very important for your CPU cooler system, and especially important for the PUMP unit in that. Failure of case fans attached to SYS_FAN headers is less critical.
I gather in your system there is a cable from the PUMP unit and a separate cable that somehow powers BOTH rad fans.Ideally BOTH should be controlled by headers using for guidance the temp sensor inside the CPU chip.That IS possible if you connect the RAD FANS to one of your SYS_FAN headers and configure that header properly. To connect them both to one header you use a SPLITTER I believe is supplied with your AIO system. For that I suggest SYS_FAN2 near the top front of the mobo. Your CASE VENT fans can then be connected to the other two SYS_FAN headers.
See the BIOS Setup manual, p. 2. If you are not familiar with this system, you get into it by holding down the "Del" key right after pushing the front panel On button. Hold it down until your screen shows the opening of BIOS Setup. Wait for the Main Menu (p. 4). Use F6 to get to Smart Fan 6 (p. 6).
Start at left side and choose the CPU_FAN, where your PUMP is plugged in. For that at upper right set
Fan Speed Control to Normal
Fan Control Temperature Input to CPU
CPU_FAN Control Mode to PWM, not Voltage or Auto
CPU_FAN Stop to DISabled so it will not stop
Fan Fail Warning to ENabled
Now at the left choose the SYS_FAN2 header that you will use for the RAD FANS. Set it exactly the same as the above.
While you are there you can set options for the two other SYS_FAN headers where you have CASE VENT fans plugged in. Set them all that way EXCEPT:
Fan Control Temperature Input to Motherboard
When you have all these adjusted, use the Esc key back to Main Menu, then F10 to get to the Exit Menu p. 29. There choose Save & Exit Setup to save these settings and reboot.
This uses a design quirk of fans. Your PUMP is wired just like an old 3-pin fan. PWM-style fan signals sent to such a fan can NOT control its speed so it always runs full speed, just as your PUMP is supposed to do. But the RAD FANS are VERY likely of the newer 4-pin designs and their speeds WILL be controlled with those signals. So the pump and rad fans will operate as intended with fan speeds controlled automatically according to the temperature sensor inside the CPU chip. The PUMP speed signal will be monitored for possible failure and quick action taken if that ever happens. The SYS_FAN2 header can monitor the speed of only ONE of the rad fans for failure, so from time to time YOU should just look and verify that both are working. Neither the pump nor the rad fans should ever stop.
Meanwhile your case vent fans on the two SYS_FAN headers also will be controlled automatically, but guided by the temp sensor on the mobo. They also will be monitored for failure, although that would not cause a system shut-down.