I recently designed a build on PC Partpicker, which said it had a power consumption of 318W (with 20% allowance), so I chose the Antec EarthWatts EA-380D.
However guides here (and the official Nvidia site) say that I need at least 450W for my GPU. I am not sure why this is, could someone please explain? If it's allowance for OCing, SLI etc then I do not plan to do any of that.
If 380W is a bad idea however I will go for a 520W SeaSonic S12II-520 Bronze.
Here's my spec:
Fractal Design Define Mini MicroATX Mini Tower
You have to go for Seasonic 520W between the two. Normally, better quality components are used in higher wattage psu. You have to consider the efficiency of psu will reduce overtime too. For the Antec 380W, your build will be a little stressful while the Seasonic 520 will handle with ease.
that earthwatts 380 is perfect. it is continuous power, not peak, and has a 6 pin PCI-E power connection. nvivdia recommends PSU wattage that they consider "safe" w/o knowing the quality of the user's PSU - such as most PSUs list the "peak" power or have weaker (under 80% of the PSU's load) 12 volt rails.
that 380 is fine as long as you are not going SLI in the future.