Question New build not booting up at all, except for RGB lights ?

[Segarelli]

Hey there, my newly built PC won't turn on at all. All the components are brand new.
However, when the PSU is turned on, the RGB lights on the mobo do turn on for a few seconds, but pressing the power button does nothing: no fans are spinning nor any other lights are turning on (of course nothing turns up on the monitor).
What we've tried (not necessarily in this order):

• Shorting the power pins (after verifying that the front panel connectors were wired the right way)
• Reattaching the 24 pin and 8 pin mobo cables, same for the GPU cables
• Trying one RAM stick at a time
• Installing the extra standoffs on the case and screwing them in (the mobo was previously hanging on 6 out of 9 screws, but the standoff holes were matching with the case, so it couldn't have possibly shorted the mobo)
• Plugging the PSU in the wall socket and in the UPS
• Removing the CMOS battery for a few minutes
• Reseating the CPU (no pins were bent) and the cooler
• Checked that the firmware is compatible with the CPU (from the last 4 digits on the mobo's barcode)

I doubt it's the PSU as the aforementioned rgb lights wouldn't turn on at all if it wasn't receiving any power, right?
I also don't think the mobo is fried as I didn't expose it to static electricity nor did I feel anything while building.
I should mention that the GPU is in the second PCIe slot (I don't think it matters but maybe it has something to do with all this?)

Any help would be appreciated.

Specs:

• Case: MSI MAG Forge 100R
• Mobo: Asus Prime B550 PLUS ATX
• GPU: Gigabyte RTX 3070 Eagle OC 8GB
• SSD: Crucial P2 1TB
• CPU: AMD Ryzen 5 5800X
• RAM: G.Skill Ripjaws V DDR4 3600 MHz 32 GB (2x16GB) CL18
• PSU: Cooler Master V-Series 750W 80 Gold
• CPU Cooler: Scythe Fuma 2 Rev. B

 

[Ralston18]

Does the build have a speaker?

One clue may be beep codes: some combination of long and short beeps (listen carefully) that indicate a problem of some sort.

Refer to the motherboard's User Guide/Manual regarding how to connect a speaker.

Post what, if anything, that you hear.

 

[Segarelli]

Does the build have a speaker?

One clue may be beep codes: some combination of long and short beeps (listen carefully) that indicate a problem of some sort.

Refer to the motherboard's User Guide/Manual regarding how to connect a speaker.

Post what, if anything, that you hear.

I forgot to mention it in the OP, I did plug in the speaker too, but as I've said nothing boots at all, not even that

 

[Ralston18]

This motherboard?

https://dlcdnets.asus.com/pub/ASUS/...PLUS/E16536_PRIME_B550-PLUS_UM_WEB_051420.pdf

[Do verify that I found the applicable User Manual/]

Referring to the User Manual go page by page to check everything and confirm that all installed components are supported. Be sure to confirm via Asus's QVL lists.

Also double check that all connections and configurations are correct or otherwise as they should be with respect to the build. Refer to the applicable installation guides/manuals for those components as well. And include the case as well.

Regarding the PSU - new, used, refurbished? History of use: heavy gaming, video editing, even bit-mining?

PSU's provide three different voltages (3, 5, 12) to various system components. So it is possible that some things appear that they have power and are "working" when they really are not working.

Modular PSU - correct? Were there cables from other modular PSU's used in assembling the build. Modular powers cables should not be mixed or interchanged.

Use only the cables that came with the installed PSU.

Lastly:

"Installing the extra standoffs on the case and screwing them in (the mobo was previously hanging on 6 out of 9 screws, but the standoff holes were matching with the case, so it couldn't have possibly shorted the mobo) ."

l would not take that for granted. Take a close look at the standoffs and also the area around the I/O panel.