BM Vega 56 + LG Ultrafine 5K on 6,1 - reporting as connected to dGPU
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BM Vega 56 + LG Ultrafine 5K on 6,1 - reporting as connected to dGPU  


Trusted Member
Joined: 3 years ago

I know my setup is a rarity, but at my wits end and looking for any thoughts. I’ve got a 6,1 Mac Pro and the BlackMagic eGPU Pro Vega 56 connected to a TB3 Ultrafine 5k. I’ve got the setup working in MacOS and Windows 10 1903. My problem is, unless I use a DisplayPort or HDMI monitor, Windows believes the UltraFine is connected to one of my D700’s opposed to the Vega 56. This introduces extreme lag and hurts FPS. I’m playing Anthem, with the Ultrafine I get about 15-20FPS (confirmed running on Vega 56 via task manager) and if I swap to a DisplayPort or HDMI display I can get 55-70FPS with the same settings. I would love not to have 2 monitors on my small desk and just use the Ultrafine as it’s my daily driver.

The bummer is, this same setup connected to my MacBook Pro 15” 2017 seems to work without issue. The Ultrafine is reported connected to the Vega 56 instead of the RP 560 internal. Why would the MacPro behave differently? Could this be because TB2 on the MacPro is somehow bypassing the eGPU and daisy chaining the display opposed to connecting via the eGPU like the TB3 MacBook does?

This topic was modified 1 month ago

2017 15" MacBook Pro + 16GB + Radeon Pro 560
2013 Mac Pro
Blackmagic Design Radeon Pro 580
Mantiz Venus - Radeon RX 580
LG Ultrafine 5k - Dual

2017 15" MacBook Pro (RP560) [7th,4C,H] + RP 580 @ 32Gbps-TB3 (Blackmagic eGPU) + macOS 10.14.5 & Win10 [build link]  

Noble Member
Joined: 3 years ago

If Windows thinks the LG UltraFine 5K is connected to the D700 then does that mean it is limited to 4K 60Hz?

Did you try connecting the display after the computer has booted? Or before it has booted?

Did you try connecting the BM with display connected after the computer has booted? Or before it has booted?

Does the BM have the latest firmware? (If not, then consider using Ubuntu to save the current firmware and post the result here before updating)

If this can't be fixed, then you would need a method to break the Thunderbolt link between the display and the Mac Pro while allowing the eGPU to provide output to the display. This could be done with a Thunderbolt 3 add-in card but the BM eGPU Pro only has one DisplayPort output. The outputs from the Thunderbolt port cannot be trusted in your setup - or maybe Thunderbolt to DisplayPort conversion directly from the eGPU uses DisplayPort signals from the Vega 56 - have you tested that option with a USB-C to DisplayPort adapter or cable?


Mac mini (2018), Mac Pro (Early 2008), MacBook Pro (Retina, 15-inch, Mid 2015), GA-Z170X-Gaming 7, Sapphire Pulse Radeon RX 580 8GB GDDR5, Sonnet Echo Express III-D, Trebleet Thunderbolt 3 to NVMe M.2 case