Are there any parts that can't be upgraded if you build your own computer?

When building an computer from scratch, most stuff will have to be bought new such as ram will evantually have to upgrade because they'll change from DDR3 to DDR4 or so, which your motherboard won't be compatible so you'll need to upgrade your motherboard, if you upgrade your motherboard you'll have to consider a new processor because the old one most likely not fit. The graphic card won't need to upgrade as much or the power supply, hard drive, cd/dvd drive, sound card, or case. Believe me I built my all the time and that is how it works. You'll eventually want to just build a new one after 5 to 6 years.