Having trouble with first boot. Please help.

Mar 22, 2018
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Hey guys! This is my very first build, here are the parts inside:

AMD Ryzen 1600 Processor
ASRock AB350M HDV Motherboard
8GB Corsair Vengeance LPX DDR4 3000MHz Ram (x2)
ADATA SU800 M.2 128GB Ultimate 2280 3D Nand SSD (boot drive)
Seagate BarraCuda 1TB 3.5-Inch SATA III 6 Gb/s Internal Hard Drive
Corsair Semi-Modular ATX CX550M Power Supply

So I've put everything together and plugged everything in the right places. When I power it up the lights turn on and the fans start spinning but theres no input detected on the monitor. I've tried plugging the HDMI in both the GPU and the mobo. Also it doesn't detect my keyboard either. What am I missing?