Thank you all for your valued and experienced advice.
Sadly PC-part prices are totally different in Denmark and my budget is limited for an eleven year old entry-level pc gaming fortnite RGB experience. But I'm taking all your advice going for the 2600, upgrading space at the cost of it being SATA SSD in stead. Dual memory 2x4 or 2x8.
In my nephews eyes RGB = better than the actual FPS or snappiness. Sadly.
I'll update the full build, and hope that you'll bear with me and aid me once again