Here's a test setup with an R9 380X and i7-3770K OC'd to 4.8GHz: http://www.hardocp.com/article/2015/11/19/asus_strix_r9_380x_directcu_ii_oc_video_card_review/2

Here's how much the whole computer uses under full load: 323W. That's a value taken from the wall. Going by the 90% efficiency of their PSU, that's 295W of actual power consumption.

Here are power consumption tests of R9 380X alone, isolated: 171W average and 179W peak.

So yeah, if you had a 450W PSU, it would only be loaded to about 2/3rds with that exact setup. And you won't even hit that, because your CPU will consume less power - since it's not an older i7 and it's not overclockable.

And for the record: power supplies are rated for their full output power, at continuous load. You could run an EVGA 500B, Corsair CX500, or XFX TS 550W at 100% load, 24h/7, for years, and not worry a single bit. Don't treat power supplies like they're made of paper - leave that for the likes of Diablotek, Logisys or other dishonestly rated units. Running a normal 500W PSU at 450W load will not decrease its lifespan to a few months.

A good 450W really would run it, although some more extra room is a definitely good thing.

I saw, I was going to delete it, but never did.

I didn't ask if it was enough

So you're willing to overspend for higher wattage? This build only need 550w.

As orion said , the TT Smart isn't necesarrily bad, but not amazing for the price. The better Seasonic S12II is only a bit cheaper, while having better value.

If you are looking for something in between the price of the G2 and the SmartM, look at the EVGA GQ, or Rosewill Valens. Both great power supplies.