'MakeMKV', 'Handbrake' or 'VidCoder', those are the tools you'll need to convert a DVD into single video files.
Don't play around with standard presets, until you have a good grasp of what those values mean and how these can affect the result.
Patience is required, regardless of the "horse power" your computer may have. Especially when using HEVC (a.k.a. x265/h265), the conversion is very intensive for RAM and CPU.