How much wattage do I need (if that's a word)

[DaJoeMeister]

In a build with a i5 4670k, r9 270x, and 8 gigs of ram what watt power supply would leave me with enough room for a graphics card upgrade in the future

 

[Jameson Clark]

Try going to pcpartpicker.com and inputting any and all components you will be using, it will have a section telling you the wattage required. Now that number will certainly be a bare minimum, at stock. For over clocking will take more and to assure you aren't maxing out your psu try to double the value it provides. Your PSU will operate at peak efficiency around 50% it's max output.

 

[Jameson Clark]

For example my build: http://pcpartpicker.com/parts/partlist/

Now I didn't quite double but obviously doubling is more than enough the higher the base wattage gets.

 

[realchaos]

You should be fine with 500-600w. This would be a great option: http://pcpartpicker.com/part/xfx-power-supply-p1650snlb9
Even though 650w is overkill, it is the same price as the 550w model and it should be able to handle any future upgrades that is not crossfire.