Mac Pro (2013) 3 Displays 2560x1440 and Mini DisplayPort to Dual-Link DVI Adapter

Hi,

I have a Mac Pro 2013 and I need to use 3 Displays on it with 2560x1440 Resolution, I connected them to my Mac Pro using 3x Mini DisplayPort to HDMI ( Support till 4K - not made by Apple), now I have 2 Displays working good with 2560x1440 Resolution but the third Display was deactivated.

I read this on Apple Website :

Connect a DVI display

Your Mac Pro (Late 2013) supports DVI displays using Mini DisplayPort to DVI adapters. Use a single-link DVI adapter such as the Apple Mini DisplayPort to DVI adapter for DVI displays with a resolution up to 1920x1200. Use a Dual-Link DVI adapter such as the Apple Mini DisplayPort to Dual-Link DVI adapter for resolutions up to 2560x1600.

Your Mac Pro (Late 2013) supports a total of two single-link DVI displays. If you connect a third DVI display using a passive adapter or a display using HDMI, it causes one of the three displays to become inactive.

Connect more than two DVI or HDMI displays

Mac Pro supports a total of two DVI or HDMI displays when connected via the built-in HDMI port or using the Apple Mini DisplayPort to DVI adapter. To connect additional DVI displays, use an active DVI adapter like the Apple Mini DisplayPort to Dual-Link DVI adapter. You can connect up to six active adapter DVI displays. This requires a powered USB hub since Mac Pro offers four USB ports and you need six USB ports to connect the Dual-Link DVI adapters.

My question is: I must buy 3x Active Apple Mini DisplayPort to Dual-Link DVI adapter or only 1 for the third deactivated Display?

Best Regards