Question My PC doesn't boot after i upgraded my GPU

[gligaugandastrong]

I just bought a RX 560 4GB for my PC, i used to have a AMD Radeon R7 200 series. But when i plugged the new GPU in my PC doesn't boot up, all the fans in my computer spin including the GPU fan but the monitor doesn't show anything, and my keyboard and mouse don't light up. However when i plug in my old Radeon R7 200 everything works. I tried switching the HDMI cable, switching RAM slots, and removing the CMOS battery for a couple of minutes. I have a HP Pro 3400 MT motherboard, Intel i5-2400 3.10 ghz, and my power supply has about 400W

 

[Ralston18]

Make and model information for that 400 watt PSU? Age? Condition (original to build, new, refurbished, used)? History of heavy use for gaming, video editing, or bit-mining?

This GPU?

https://www.powercolor.com/product?id=1503986321#spe

RX 560 GPU specs recommend a minimal PSU of 400 watts. Another spec sheet listed 450 watts.

PSU a likely suspect....