Kid’s First Gaming Build

My son currently uses my all-in-one for gaming. It’s an i7-8700T with 16GB Ram, and a GTX-1050 4GB. 256GB SSD and 2TB HDD.

We are at a crossroads with his games becoming more demanding and the computer getting older.

I’ve picked him a case (Phanteks XT Pro Ultra Mid-tower) that will be a Christmas gift as a “kickstart” to a PC build.

Is it worth it to rip the components out of the all-in-one and use them as we build, or do I just need to start fresh?

His budget will be VERY limited as he is 12 y/o and doesn’t have a job…just chores/grades money. He has $250 saved up and maybe sell some toys…so let’s say $600 top-end budget.