550w is more than enough for that, your whole pc will be using less than 300w.
That said, the reason for 550w is that that puts your usage at @ 50% ish. The best results thermally, efficiency, power output ripple etc all happen in the 50%-70% load range.
So heavy gaming will put your pc in the best power output health area.
All that said, power and quality are not synonymous. You can get absolutely junk 700w units I'd not trust not to start a fire and top-shelf quality 400w units.
If the prices are somewhat equitable (always shop sales items!) a better quality 650w would be a better purchase than a decent quality 550w.
So Which you buy is often more important than What you buy