Review of your PSU
"In the end, it may not matter because the 450 B3 has other, more serious problems. It looks like Super Flower made a huge mistake in its design, which poses a major safety risk. We noticed that the over-power protection triggering point is set way too high. Even under normal operating temperatures, one of the primary FETs in our store-bought sample, along with some other components, blew up. Either SF should set its OPP point much lower or use components able to handle higher amperage. We were also disturbed by the fact that, after the primary side shorted out, the PSU's fuse didn't blow. Every time we applied power, we saw sparks. Obviously, that's a fire hazard. "
As for the GPU and CPU at 1440p, you'll probably be fine. Depending on the game, you may have to adjust some of the in-game video settings.