Dual Graphics Cards Performance Hit

[GapManCA]

Budget (including currency): $3000 CDN

Country: Canada

Games, programs or workloads that it will be used for: WoWS/WoT

Other details Aorus Elite, 32GB Vengance, Samsung 980 NVMe 500G,

 

Looking to build an all AMD rig.  While currently no Ryzen 5000 series CPUs are available, I may go Ryzen 3900x if the price goes low enough.  I will eventually get a RX6800, but will use one of the 1080s that I have until they become available.  My question is I am looking at getting into streaming my game play.  While I know that in the past running 2 x video cards would make the PCIe ports go from x16 to x8, is that still the case with the new X570 boards?  I am looking at getting a cheap Radeon 590 or 5500 to run OBS against if there is no performance hit.  The reason that I will not keep the 1080 in the rig is because I do not want to worry about driver conflicts between the 2 brands.  Also that GPU is destine for the computer that is connected to my TV.

[Electronics Wizardy]

Yup using the other slot makes both run at x8.

 

Using a second gpu for obs isn't a great idea, and those amd gpus are much worse than nvidia gpus for video encoding, id go cpu encoding here.

[brob]

According to the Aorus X570 Elite specifications with a Zen 3 cpu, one x16 slot uses 16 cpu PCIe 4.0 lanes. The other x16 slot uses 4 chipset PCIe 4.0 lanes. Theoretically there would be no impact on the principal cpu and the secondary one would have bandwidth roughly equivalent to 8 PCIe 3.0 lanes.

 

With a Zen 2 cpu the slots run PCIe 3.0 with same sources and lane counts as noted above.