I've tried Watt calculators but all of them are outdated and I can't find the parts.
I think you were wise to try a calculator. The problem going with what the GPU maker suggests is they are only guessing when it comes to the rest of your components. They have no clue how many, or what type RAM sticks you have, number of drives attached, fans, other expansion cards, and more. So they pick an arbitrary number based on what they think is the "average" system. And each GPU and graphics card makers have their own arbitrary numbers. Also, only you know if you might be adding more RAM, more drives, or a bigger or second graphics card in the next year or two. So you need to think ahead, and plan for any upgrades - if you want this PSU to carry you through.
I too recommend the eXtreme Calc, but sadly, and inexplicably, the GTX 980 is not listed (I have reported it, BTW). So you don't have much choice, but to go by the GPU maker's recommendation.
If you are not overclocking and not a hard core 3D animated gamer or do CAD/CAE work, then I agree a quality 550W supply should do. I would urge you to look for a supply from a reputable maker and that it is 80 PLUS
certified to ensure at least an 82% "flat" efficiency rating across "all" realistic
loads. I prefer Corsair, Seasonic, and Antec PSUs, but understand achieving a high, flat efficiency requires quality design, quality parts, and quality construction - regardless the brand name stamped on the case.
Note it is that "efficiency" rating others were referring to about wall current. What it means is with a PSU rated at 85%, for every 100 watts pulled from the wall, 15 watts will be wasted in the form of heat.
Unfortunately, there are MANY new, inexpensive PSUs on the market - including from reputable makers, that are NOT 80 PLUS Certified that may advertise 85 or 87% or higher efficiency rating. But if not 80 PLUS Certified, they likely achieve that high rating at just one load point (typical for basic, rudimentary power supplies). But we all know that computers present a variety of demands on PSUs from near nothing at idle, to 100s of watts when pushed. So get a supply with a "flat" efficiency curve across the full spectrum of "expected" loads to ensure your supply is delivering good, clean, stable power at all load levels.
The good news is that monster GTX 980 is less power hungry than many older less capable cards.