Braegnok
My Z590 Dark has yellow caps. 
 

So does X570 Dark.
 

X570 FTW as well.
 

Yellow is the new black. 

ty_ger07
It's an audiophile marketing thing. At some point EVGA got the opinion that yellow caps marketed better to audiophiles.
Also notice the exaggerated ground plane around the audio section for the z390, even though there isn't any actual via stitching in that layer.
It's a marketing thing.
I think my earlier reply might have confused some folks. I wasn't stating that audiophiles necessarily want yellow capacitors. It was a tongue-in-cheek response about manufacturers thinking that is what audiophiles want.