I tend to recommend a 3 year cycle. Year 1 upgrade peripherals (speakers, monitors, maybe chair, keyboard, mouse etc) year 2. Upgrade video card and hard drives. year 3. Upgrade motherboard, ram and cpu. Year 4 repeat year 1
With this you can you can do 95% of the latest stuff with “good” stuff (think XX70 cards rather then 80 or 90 series) since you are never that outdated on any portion.