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What resolution would you be playing at? Full-HD or higher? Do you have a monitor?
Here you can see when gaming the peak power usage is around 240-250W so I'd say any solid good-quality 550W would be enough. You can look at 650W units too to have some head room and possible future upgrade which might require more power.
There's mention of even momentary 300W spikes in the same review but even if that happens with your card too with a 105W CPU that's around 400W and a good 550W would cover that.
Another issue you have to keep in mind is the number of 6+2-pin auxiliary PCIE power connectors the card you want t buy needs and choose PSU accordingly, although decent 550-650W units usually come with at least two 6+2-pin connectors.
How much do you plan to spend on the PSU?