can i use following adapter
Mini DisplayPort Dual Link DVI, Version HDCP ON Active Adapter
to connect 3 dvi LG 22MB37 displays to mac pro late 2013 ?
You can connect six displays to the Mac Pro 2013. You can connect two displays per Thunderbolt port (using a Thunderbolt 3 dock/display/device/adapter or multiple Thunderbolt 1/2 docks/displays/adapters), but only two displays per Thunderbolt bus. There are three Thunderbolt buses. Each Thunderbolt bus has two Thunderbolt ports. Connect one display per port or two displays to a single port.
The LG 22MB37 is only 1920×1080 60Hz, so you don’t need a Dual Link DVI adapter. A single link DVI adapter is sufficient (single-link DVI adapters don’t require USB power) – that includes DisplayPort to HDMI adapters which you can convert to DVI with a HDMI to DVI adapter.
A Dual Link DVI Adapter will work with single link displays (DVI or HDMI). Dual Link displays (2560×1600 60Hz or 3840×2160 30Hz) will be limited to 1280×800 60Hz or 1920×1200 60Hz or similar resolution if used with a single link DVI or HDMI adapter.
It’s possible the single link DVI cables require DisplayPort Dual Mode (DP++) and that the Mac Pro’s Thunderbolt 2 ports don’t support DisplayPort Dual Mode.
DisplayPort Dual Mode is a passive conversion from DisplayPort to HDMI – the GPU outputs an HDMI signal using the DisplayPort pins and all the adapter needs to do is level shift the voltage.
Some Thunderbolt docks may have DisplayPort ports that support DisplayPort Dual Mode.
DisplayPort to Dual Link DVI adapters are active adapters – they contain a chip that converts DisplayPort protocol to DVI/HDMI protocol – so you should have no problem with those.
One think to remember about DisplayPort to Dual Link DVI adapters is that they usually require four lanes of HBR to do dual link DVI resolutions such as 1440p60 or 4K30 (the converter chips are too old to support HBR2 link rate). A USB-C dock that supports USB 3.x will have a DisplayPort output that is limited to two lanes unless the dock contains an MST hub to convert 2 lanes of HBR2 or HBR3 to 4 lanes. This is not a concern for single link displays – two lanes of HBR is sufficient for 1080p60.