Question System won't POST with Shapphire RX 570 Pulse 4GB installed ?

[Mr.Bear]

Hello, i bought an Shapphire RX 570 Pulse 4GB, that was modded for mining, i've flashed it back with the original bios and worked like a charm on 3 computers:

1. Z97 pro gamer with an i7-4790k, 16GB RAM 2133 mHz, and a 750W power PSU run like a charm
2. B450m-a prime form Asus with a Ryzen 5 1600X, 8GB DDR4 2400mHz, 500W PSU, worked
3. Q9550 processor on a B5Q PRO motherboard with 8GB of DDR2 RAM and a 450W PSU worked !!

But, when i went to install the video card on a B450 pro4 AsRock with a Ryzen 5 3400G processor and 8GB of DDR4 Corsair Vengeance lpx 3000mHz 8GB single stick and a PSU Sesonic SII 520W it will not post anything, monitor says no signal, and nothing from there, all the fans are spinning, I did the motherboard bios update to the last one, nothing. Checked all the cables form the monitor, i am plugging the HDMI in the graphics card. ( Note: the pc without the video card, works good).
I am open to any suggestions, don't know what to do more. I wanted to make the video card as a present to a little guy that just started gaming.

 

[Lutfij]

You need to mention the 3 PSU's you've used to pair with the GPU in question and their age. FYI, on the S12II, you should disable C6/C7 power states when on the latter platforms.

You should also keep in mind that you will need more than 550W of power for the entire system. How old is the S12II unit?

 

[Mr.Bear]

The Seasonic is Seasonic S12II-520 Bronze 520W, 1 year old, in warranty.
The thing is the card worked on a 450W PSU LC-Power LC6450 V2.2 450W, i know the specs of the card says 500W or above, but i tested form curiosity.
The Corsair one is CX500 over 6 years old.
And the last one 750W is Super Flower Leadex III Gold, 80+ Gold, 750W over 4 years old.
Note: I even put on this build The Super Flower Leadex III Gold, 750W PSU, and still didn't post. Same story, all fans spins, mobo lights are on, but no post.