Existing set up, I can not work with double screen in Radeon 570.

Hi guys, how are you?

I am here looking for your help because I have not had much experience with AMD and I do not know what may be happening. I'll summarize it fast...

I'm have A CPU: Core i3 7100. Mobo: GA-B250M-DS3H. RAM: 8 GB GPU: An Classic Gt 720 & Shaphire Radeon RX 570. SO: Mojave 14.0. & High Sierra 13.6.1

I have a set up working properly, with a nvidia 720 gpu. I have two SSDs, one for the general purpose, with perfect High Sierra, and one of tests with Mojave, which does not work so well, because the gpu does not support Metal. Due to this changed to a Radeon RX 570 (It was about time!). In each of the OS I removed the nvidia web drivers, with the Cuda I have not found the form.

I made the physical change of the gpu, and did tests of operation in Windows, with the same set up that I have for Mac. It works well, with both screens for HDMI and DVI.

I started Mojave and gave an image on one of the screens without problem (hdmi) and the other was black, there was no signal, but on but black. Start High Sierra and it also gives an image in one screen, but when connecting the other both remain totally black and the system does not recover from it.

Looking deeper and reading a bit for the config of high sierra active RadeonDeInit, but there was no difference. After a while I realized that the Ketu Lilu and WatheverGreen were no longer needed, as I read in several threads. The interesting thing is that if I delete these kexts both Mojave and High Sierra systems go into panic mode. Or so it seems, because the system is blinking and the screen is turning off so fast that I can not see what it may be...

I suspect that the power supply (450w real) may have something to do because after several hours of playing on Windows it can not stand and it goes off. And thinking that Mac tries the components to his maximum power in the boot, I do not discard that it has something to do. But in Windows the computer shuts down completely, in this case it flashes, the system stops making effort but stays on (apparently in panic mode, because even with verbose mode it does not know anything).

On the other hand the system starts well when it has these kexts in the boot, in addition the gpu is detected without any modification, in High Sierra it seems that the acceleration works, the system does not feel slow. The. Mojave if it's a little slower.

While I can make a change of power supply, I would like to know what you think, if someone has encountered this issue or something similar, and if not, what they think may be happening. I thank you very much for any ideas or suggestions that you have in mind.

Thank you very much. :3

EDIT: A couple of interesting data, both screens are detected by the system, in THE System preferences I can adjust both, and all applications can be dragged to the other (which is a black block).

Also, if I try to start only in dvi, no signal is sent, all graphics are lost just after the system leaves Clover.