correction, cheap asus board has temp issues, high end ones, don't.
TUF is a really basic board that cut down lots of useful features. here is the tierlist for asus, (ROG non-strix > ROG strix > PRIME> TUF)
ROG non strix is expensive but very solid, ROG strix are expensive, but as long as you don't do anything crazy, they are okay.
PRIME has some good and some bad. (some are cut down of the strix board, which is okay, where sometime it's the glorified tuf board with fancy look) TUF brand made in the pass 2 year is just bad.
the vrm doesn't look very impressive, i won't be surprise if it can't deliver the max 4.2 Ghz@ all core turbo boost speed.
gaming and normal use are likely to be fine, but if you are doing rendering, or push CPU to its limit, the power draw is quite high.
and the vrm will get hot,
typical 4 + 2 phase vrm, should've been fine with i5 8400, but i7 8700. ideally, you would like to have a 6+2 or a mimic 8 phase (big 4 phase).
ideally, you don't want to push your vrm to it's limit with daily use. as the heat generate can quickly shorten the lifespan of the components.
my suggestion is that if you are only using it for gaming, you can probably keep it, and make sure to have some good air flow in the cpu, to cool the vrm and cpu.
if you are doing rendering, or other cpu intensive work, get a better board. for asus brand, strix 360-f looks much better.