CPU / GPU combination

I'm thinking either:

I3 8100 + RX 560 2gb (240 €) or i5 8400 + used Radeon HD 5870 1 GB or used R7 250x 2GB (207-217 €)

The goal is a High Sierra build for light final cut pro work.

What do you guys think? Maybe get the extra 2 cores i5 work an old gpu, since final cut mostly uses CPU in rendering / export? Intel's Quick Sync works with either CPU, they have the same gpu.