Question I bought new CPU and mobo and my PC won't work, what am I doing wrong?

[blaziiN]

So the other day I bought the i9 9900K and today I bought the Aorus z390 elite mobo, And I've built a few PCs in my day so I'd say I'm mediocre at best, but can't figure out the problem here. It powers on for maybe 1-2 seconds and immediatly shuts down.
I'm pretty sure nothing is connected wrong or anything like that.
I'd need some help please. If u want more detail I'd happy to give it to you.


Specs :
Intel® Core™ i9-9900K Coffee Lake Refresh
ASUS ROG STRIX-GTX1070-8G-GAMING
Corsair Vengeance LPX Red 16GB
EVGA Supernova G2 750W
Gigabyte Z390 AORUS ELITE

If there more things u guys need let me know.

 

[blaziiN]

Let me note that the only new parts are the mobo and the CPU, all the other stuff worked fine with my older MOBO and the RAM and PSU

My old CPU was a i7 7700 and I can't remember the name on my older MOBO sorry.