Newly built computer does not POST

[tjknejrnbtkjw4bk5jbwkejb]

This does not apply to any particular motherboard anymore, after solution was posted.

 

I just built my first desktop. It doesn't POST though. When I press the power button, the power light comes on and the fans start spinning. They are on for 10-20 seconds, until they turn off and back on (reboot?). This repeats, until I turn the computer off. I hear no beeps at any time and I have let it reboot(?) around 10 times with no success. I've tried clearing CMOS and trying each RAM slot with a single stick. Here are the computer's specs:

 

Processor / APU: Ryzen 5 2400G

Mobo: ASRock B450M Pro4

RAM: Kingston HyperX Predator 2 × 4 Gb DDR4 3000 MHz

HDD: WD Blue WD10EZEX 1 TB 7200 RPM

SSD: Kingston A400 120 Gb

Case: Fractal Design Core 1100

PSU: Corsair CX450M

Wi-Fi card: TP-link TL-WN881ND

 

EDIT #1: I'm not 100% sure, but it seems that the computer accesses the HDD (empty) for a few seconds

[tjknejrnbtkjw4bk5jbwkejb]

It seems to have been just my stupidity. The RAM wasn't well seated. If you have this problem, make sure the RAM clicks in, and see on the side of the RAM while seated if you can see the golden pins. If you can, try to apply more pressure on the side you can see the golden pins.