Question ARGB Fan flashes when PSU connected

[FrutyX]

I've recently purchased an ARGB Fan (Asus TF120), I have it connected to the 3-pin LED header (D_LED2) and to 4-pin CPU_OPT (I have it in my BIOS set that it works like a regular system fan), full specs below.

There is a strange behaviour I have noticed, but I was kinda hoping that it's normal (doing a check?). I was digging in my PC, so I had it without power, and then, every time I connect the PSU to electricity, this ARGB fan flashes, it's just a white flash, nothing else. This does not happen when I turn the PC on. I have 3 other Non-(A)RGB fans, they are not doing anything, and 2 RGB fans, they don't react to power as well.

I really wouldn't want to short it, if that's the case, but I am very sure I have connected everything properly and I have zero problems with my PC, it runs as expected, I can control and set all those fans, ARGB/RGB leds can be controlled via software, no problem there.

Sounds like a small issue, but I wouldn't want a small issue to burn down my whole computer.
Thanks.

Specs:
Case: MSI Mag Forge 100M (All fans placed)
Motherboard: GIGABYTE B550 GAMING X V2 (BIOS F16)
Power supply: Corsair RM750x (2021)
CPU: AMD Ryzen 5 5500 (No OC)
CPU Cooler: SilentiumPC Fera 5
Memory: Kingston FURY 16+16GB KITS (4x8) DDR4 3200MHz (XMP)
Graphic Card: SAPPHIRE PULSE AMD Radeon RX 7600 8G
SSD (OS): Samsung SSD 860 EVO 250GB (TRIM on)
SSD 2 (Games): Samsung SSD 870 EVO 500GB (TRIM on)

Edit: Apparently, this is because I have LEDs set to OFF in my BIOS when the PC is off, so I suppose that when I connected the PSU it switches the saved BIOS settings from the CMOS battery to electricity mode and blinks for a second because it realized they are meant to be off? Is that possible?

 

[FrutyX]

Decided a vid might be better, hope it helps:

I left the PC connected, did this only via the PSU button.

 

[Ralston18]

Starting with:

"I've recently purchased an ARGB Fan (Asus TF120), I have it connected to the 3-pin LED header (D_LED2) and to 4-pin CPU_OPT".

= = = =

To me "and" (my underline in the preceding sentence) implies at the same time.

I think of 3 pins being 5 volts and 4 pins as 12 volts.

Are you using only the cables that came with the Cosair RM750x? No extenders/adapters etc.?

Try to explain or diagram the connections being used.

 

[FrutyX]

Well, the fan comes with two cables, I have them both connected to the motherboard, one is your regular 4-pin fan header (in this case CPU_OPT, normally it would be in SYS_FAN but I would need another splitter) and the other is so I can control the ARGB, it's a 3-pin and connected to "Addressable LED Strip Header" (called "D_LED2", the header is 5V).

For the cables, the PSU ones are original, I do have one 4-pin AKASA PWM fan splitter (from 1 fan header to 2), but this new fan isn't connected to it.

 

[CountMike]

Well, the fan comes with two cables, I have them both connected to the motherboard, one is your regular 4-pin fan header (in this case CPU_OPT, normally it would be in SYS_FAN but I would need another splitter) and the other is so I can control the ARGB, it's a 3-pin and connected to "Addressable LED Strip Header" (called "D_LED2", the header is 5V).

For the cables, the PSU ones are original, I do have one 4-pin AKASA PWM fan splitter (from 1 fan header to 2), but this new fan isn't connected to it.

In that case, 4pin is for fan's motor, nothing to do with ARGB LEDs. Fans can run without (A)RGB lights, and lights without fans turning.

Difference between CPU_OPT fan and SYS_FAN is in which temperature sensors they are set to react on. Although some BIOS allow to change the sensors most usual is for CPU_FAN to use CPU temperature and SYS_FANs some other temperature sensor on the MB depending on which header, most often VRM or chipset.
As far as LEDs on fan(s) is concerned that's fairly normal to at least flash for a second. When you switch PSU on it applies power to parts of MB including fan and light controllers before they can keep them off until system fully starts. It's not unusual for lights to flash and/or fans to twitch at that time.

 

[FrutyX]

As far as LEDs on fan(s) is concerned that's fairly normal to at least flash for a second. When you switch PSU on it applies power to parts of MB including fan and light controllers before they can keep them off until system fully starts. It's not unusual for lights to flash and/or fans to twitch at that time.

This is the answer I was looking for, I wanted to be sure this isn't a problem, that it's normal. Thank you.

About the CPU_OPT, yes, I am aware of that, thankfully, my BIOS has the option to change the sensor, so the fan isn't actually trying to run with the CPU.