I don’t think we are comparing apples to apples here. 315 watts in a 4x4 is going to be less heat than a 630 watt 4x4 set up with out any question. A 600w in the same set up will be more than the 315w but less than the 630w set ups.
This is negating all other factors, such as ambient temperatures, air cooling features, volume of air to be controlled, effiency of equipment, and other heat/cooling inputs that are unaccounted for (such as heat sinks).
There are a lot of factors that determine that temperature in your garden. But when negating all others it’s been proven that 2 watts is hotter than 1 watt in general.