Depends on the manufacturer of your RX570. But it seems like the RX570 can support a maximum of 5 Monitors at the same time.
Here is Sapphire Nitro+ RX570 specs as an example only: Sapphire NITRO+ RX 570 - graphics card - Radeon RX 570 - 4 GB Specs & Prices - CNET
The MSI and XFX GPUs have identical Specs as far as Max Monitors and Video Outputs:
MSI: MSI RX 570 GAMING X 4G - graphics card - Radeon RX 570 - 4 GB Specs & Prices - CNET
XFX; XFX Radeon RX 570 RS - XXX Edition - graphics card - Radeon RX 570 - 4 GB Specs & Prices - CNET
The XFX supports 6 Monitors though:
Thank you!. I am going to see if I can connect the second
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