IMO you'll learn more of the math than anything, unless you take some embedded systems track. An embedded systems track will get you working closer to the metal.
That depends entirely on what CS masters program you select. I've been eyeing the GT OMSCS for next year and you can take the entire thing almost entirely focused on low-level systems if you want, without much (if any) math beyond whatever their algorithms courses cover (one or two are required IIRC).