Question What is really the requirement for Crossfire in 2019?

clsmithj

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I thought I had all the necessary hardware to achieve AMD Crossfire but I come to find out you have to have the "Crossfire" option in the Radeon Settings to enable/disable.

I don't see this at all in my Radeon Settings. I'm running the most current Adrenalin drivers 19.4.1 , I just tried a few older versions going back to 17.9.x Crimson to see if the Crossfire option show up in a different driver but nope.

I have spent a good half of the day reading a lot different articles, but nothing really going into substantial detail on Crossfire setup. Of course I have a lot of questions.

Is Crossfire a DirectX 11 only feature? Just today I had no idea the DirectX 11 vs 12 played a role with AMD no longer referring to Crossfire as Crossfire but as "Multi-GPU" even though they still have numerous published articles that talk about Crossfire and it's requirement and mention nothing about the DirectX requirement or Operating System requirement.

Am I to believe that Youtubers showing off Crossfire setups might be all using using DirectX 11?

Does this mean they are using older versions of Windows because I thought Windows 10 is DirectX 12?


My Specs:

OS: Windows 10 Pro for Workstations
Motherboard: MSI X399 SLI Plus
CPU: Ryzen 2990WX Threadripper
Video: XFX RX VEGA 56 BlackDesign (Primary Display)
MSI RX VEGA 56 Air Boost OC
RAM: 64GB Patriot Viper DDR4 3000Mhz
Storage: Samsung 960 Evo M.2
Monitor: DELL 32" 1080p LED
 
sometimes getting multi GPU to work can be tricky. use DDU to do clean driver uninstallation. then make sure both card properly inserted on the PCI-E slot (you might need to look you mobo manual as well for the best slot to use for CF purpose). make sure all power connector are connected properly to the card. turn on your PC and reinstall your driver.

in regards to DX11 vs DX12....before DX12 all CF profile and optimization are done by AMD. with DX12 the multi GPU implementation are left in developer hands. in a sense it is no longer CF since CF use it's own API to handle multi GPU. with DX12 multi GPU support come as one of the base feature for DirectX API. now we do see in DX11 mode the game might work with CF while in DX12 the multi GPU are not working. because in DX11 (or older DX) GPU maker will be the one that provide the necessary work to make multi GPU work. in DX12 it is all in game developer hands. and most often supporting multi GPU is not a high priority for them. hence multi GPU support with DX12 most often only comes at much later since even without multi GPU game developer already busy fixing their performance issues under DX12.
 
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clsmithj

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I figured out the issue. It was because I had the Above 4G Memory / Crypto Currency Mining setting enabled in the BIOS. Disabling that setting restored AMD Crossfire setting in addition to a couple other settings I didn't have before in Global Settings.
 

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