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Depends on your gpu and cpu. My numbers are high as I went with cpu+gpu being overclocked a bit and I always add 20% as the psu will lose a bit over time and so not running it at the limit means when it drops a bit it will still work for ages. Corsair CX TX whatever are good, so long as it's not the "builder series" it's good, if you add/upgrade your graphics card that psu won't be big enough.
bequiet make really good psus so I'd say not worth a change
It looks like your psu is from this range if that helps.
http://www.bequiet.com/en/powersupply/667
Your gpu pulls 90w
CPU 180w
hdd 8w
ssd 5w
mobo 50w
ram 3w/stick
dvd drive 30w
case fan 5w
add 20% to total
I'd say get a reliable brand 650w that's 80+ rated.