> how many hi-res (4k@60hz) monitors can I drive from a single RPi 4 ?
Just one. If you connect a second 4K monitor it drops to 4k@30
> run at 4k@60hz over USB3
No. USB 3.0 only has a maximum bandwidth of 5 Gbit/s. It takes around 15gbit/s to drive 4k@60hz 4:4:4 8bit color. That was first available in DisplayPort 1.2 which had 17gbit/s available bandwidth.
> additionally, two USB3 ports.
The USB ports are all on a single PCI-E bus with a maximum bandwidth of 4Gbit/s. So technically you don't even get full speed of a single USB3 port, much less 2.
Forgive me, but since we are talking about DP 2.0 at the same time as the new RPi4, I am wondering:
- how many hi-res (4k@60hz) monitors can I drive from a single RPi 4 ?
I think the answer should be 4 since there are already two (mini) HDMI ports and, additionally, two USB3 ports.
The question is, can Displayport (or any display format) run at 4k@60hz over USB3 ?
Thanks.