This is the Specs for a Sapphire Vega64 showing it Max Resolutions: Sapphire Radeon RX Vega 64 8G Graphics Card 21275-02-20G B&H
"The front panel of the card features a variety of outputs. There are three DisplayPort 1.4 outputs and a single HDMI 2.0b output. With 8GB of HBM2 VRAM, the Vega 64 card can support a resolution of 5120 x 2880 at 60 Hz (via DisplayPort). Combined with AMD's Eyefinity, the GPU can provide an immersive gaming experience using up to four monitors. AMD FreeSync technology allows the Vega 64 GPU and your monitor to dynamically change frame rates to reduce screen tearing. "
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Display Support | Display Connectors: 3 x DisplayPort 1.4 1 x HDMI 2.0b Maximum Digital Resolution: 5120 × 2880 @ 60 Hz (DisplayPort) Multi Monitor Support: Yes |
Other Manufacturers of Vega64 may have slightly different Specs and Resolutions.