Great if you have a current board and need to upgrade the CPU but starting new. X570 motherboard and 39XX series CPU would be a better buy.
How does his compare Vs a 3700x for gaming?
Not after you factor in the motherboard costs. You would be daft to buy this now for a new setup unless you have some unique use-case to use all the lanes. A Ryzen 9 (or hell, a Ryzen 7 3xxx) would be much better value.
Yeah i saw, not allowed on hotdeals uk though i don't think due to the poor trust pilot.
X399 mobos certainly are not cheap. Min £300 is what I can find.