Question New PSU

The PSU estimate will add a certain percentage of leeway just to be safe, then add another maybe 50w for the overclock, just in case, plus another 100w for just because (actually I suppose this isn't needed, but it's just peace of mind, and also futureproofing). That takes us to about 625w. Then, you are left with either the close match of the 620w Seasonic S12ii, which would be a bit of a step down from the G2, or a round up to 650w. Even if you were to go with a G1 PSU, this would still be worth it, more so than keeping the 550w G2 PSU.