Originally Posted by Phaedrus2129
300W is on the low side. A very high quality 350W might do the job. A Corsair CX430 or Antec EA380D would do the job for sure.
A GTX260 is like a 170W card, ~140W during typical gaming. A bit more with overclocks. CPU is a good 70W, and the rest of the system maybe another 50W. Close to 300W right there during peak consumption, which is too close to the limits of a 300W, especially since most 300Ws are low on the +12V side.
Contrary to public belief, I do endorse headroom. Just not 2x your peak wattage headroom.
A very good explanation!
I like to clarify two points:
1-The 12v line is the most important one & the total wattage on 12v rail(s) is somewhat less than nominal capacity.for example a 500W PS may offer only 430W on 12v rails.
My 240-250 W estimate on 12v line has nothing to do with efficiency!
2-The op states:"...I doubt that "Your mobo & other components should use roughly around 50W" maaaaybe 20w or less..."
Now 20W is a gross underestimate.For reference,50-60 W is a much better guess
Ofcourse Phaedrus2129 can explain both points better than me