Need help! PC isn't booting!

[HilarioLikesWater]

I built my first PC. After an hour of building this computer I was ready to install Windows do get to playing some Minecraft. 

I turned it on and it booted, I set my USB drive to boot so I can install Windows, then after I selected save and exit the PC turned off.

I flipped the PSU switch off and on and tried to turn it on again but then none of the fans were spinning, an LED marked CPU flashed quickly and nothing happened.

I tested each part to see what's the problem, GPU is working, CPU cooler is plugged in correctly, RAM has been tested and reseated multiple times, did the PSU paperclip test, front panel connectors are in their right place, CMOS has been cleared several times.

 

Nothing

 

I thought it would be a dumb idea to unplug the 8 pin CPU connector and when I did, it turned on? All fans were spinning (except the white case fan cuz I haven't connected it) and SSHD was active.

 

Could it be the CPU is defective? Is the PSU defective? Did something in the mobo short out? SOMEONE HELP ME AAAAAAAAAAAAAAAAAHHH

[Mateyyy]

And what CPU and motherboard are you using?

[Haro]

38 minutes ago, HilarioLikesWater said:

Could it be the CPU is defective? Is the PSU defective? Did something in the mobo short out? SOMEONE HELP ME AAAAAAAAAAAAAAAAAHHH

full specs ?

some b450 boards dont support the AGESA code for zen 2 out of the box 

it could be that 

[HilarioLikesWater]

1 minute ago, TofuHaroto said:

full specs ?

some b450 boards dont support the AGESA code for zen 2 out of the box 

it could be that 

I am using a Ryzen 5 1600 af on a Aorus B450 m

[Haro]

1 minute ago, HilarioLikesWater said:

I am using a Ryzen 5 1600 af on a Aorus B450 m

im going to assume everything is new 

have you tried a different psu 

maybe a friends psu

inspect the cpu and make sure there isnt anything wrong with it