Building a pc and new to AMD products, I was gonna pair the 7900XTX with Intel i7 13700K but a friend of mine recommended the 7800X3D instead with the promise of a buff on performance in addition to an AMD graphics card. Is this a good idea?
There isn't any special magic that make amd cpu and gpu combo perform better.
You might not think Infinity Cache might is special magic but why shouldn’t OP take advantage of RDNA 3.
I read the question differently, like is there some sort of boost pairing amd cpu and gpu, not which cpu is better.
I would definitely pair your 7900XTX with a 7800X3D! Take advantage of infinity cache and RDNA 3. I would also download AMD Adrenaline and make sure Smart Access Memory is enabled.
According to Tom's Hardware article comparing the Ryzen 7 7800X3D to Intel Core I7 13700K depends on what you are planning on using your PC that will determine which processor you want to use: https://www.tomshardware.com/news/amd-ryzen-7-7800x3d-vs-intel-core-i9-13900k-vs-intel-core-7-13700K
Your Friend is right AMD processors do work better with Radeon due to SAM!!!
Which is the same thing as rebar.