Note the 'M' at the end of the model number. The laptop GeForce models are different (and less powerful) than the desktop models. According to the website, the

Note the 'M' at the end of the model number. The laptop GeForce models are different (and less powerful) than the desktop models. According to the website, the 840M supports "entry-level gaming", which isn't really the primary use case for Vulkan.