Doom
Absurdly violent and increasingly gruesome at every turn. It's fast, it's frantic, it's Doom. A game that needs no introduction to PC enthusiasts, this 2016 reboot brings hell's evil forces to life with updated visuals and is without a doubt one of the most eagerly anticipated launches in years.
Once a poster-child for Radeon cards, Doom is run using the Vulkan API and shows zero benefit from the addition of a second GPU. You could argue that this game doesn't really need that much power, but it's nonetheless a shame having a second card sat around twiddling its processors.