Power Tests
You would typically see video-encoding load number at around 115W if the CPU was run at stock speeds. Jacking the voltage a bit to ensure a smooth 4.8GHz increases the wattage by about 25 per cent, but 150W is barely scratching the capability of a decent PSU.
Even a gaming load of 300W is well within the remit of a 500W PSU, so there's really no need to consider anything much bigger if running a single graphics card.