I've never really checked the efficiency. I usually run around 1.25 depending on strains. Probably a gpw this run. Only 4 plants instead of 6 and 2 are not heavy yielders. I ran 2 of my usual good yielders and a blue dream which looks good but I may get 2 zips from it. The SSH around 4. 6 or so each from the tgas. I will be moving to a b3590 build later. Passive cooling except for my Carbon blower system.