Changing the DC-DC converter inside the computer may help with power droops caused by components inside the computer drawing a lot of power, but that tends to be a fairly predictable power draw, something you can control to a point (systems with a lot of HDD storage might stagger HDD spinup, you can undervolt/underclock CPUs and GPUs, etc.).
Factors outside the computer won't be helped much if at all since they affect the power that gets to the AC-DC converter segment, and can be less predictable sometimes. You either need a beefier AC-DC converter (usually a power brick in this case), or better yet, a UPS to isolate your PC from the power grid.
Speaking of UPS's though, with stuff like the PicoBox or HDPlex things that do separate the DC-DC and AC-DC converters, it would be nice if someone came with one that included circuitry to connect to and manage batteries, so that you could operate your computer more like a laptop: when the power isn't clean or is temporarily unavailable, the systems starts running on battery power, then recharges when the power comes back on.