Meanwell make among the best supplies on the market with supplies ranging from good to excellent. What they do do however is fool people with their marking/marketing. The SP-320 range which is reasonably commonly used for blinky heads is nothing like 320W across the range of voltages. The 320 refers to the product range more so than the output power. Below is a snapshot from the SP-320 data sheet. The commonly used 5V, 12V and 24V supplies supply 275W, 300W and 312W.