Ehm, why would you get the GS when the G2 is cheaper and better?
You never said anything about the price though. Is that brand new? The first thing that jumps into my head is "what's wrong with it"? That's almost half price.
I believe G2 is definitely better than GS, as GS although seasonic is G series based and the G2 is leadex, which is better
90% on that though, not 100