Question Pc won’t turn on

Jun 6, 2019
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So I’ve recently built a pc and when plugged in it will just not power on, I have noticed when plugging the 24 pin cable when it is about half way in case fans, cpu fan and psu fans will spin and the power button on my case will flash repeatedly orange. When the cable is fully plugged in I get nothing. Specs are:

Motherboard: Asrock b450m pro-f (brand new)
Cpu: ryzen 5 2600 (used)
Psu: thermaltake 550W silver (brand new)
Ram: 8gb ddr4 (used)
Gpu: unknown/none (and I don’t think is the issue)
SSD: 128gb (model unknown)