I have a DIY of the 650R, that also uses the Diablo boards. I bought the boards and managed to find 2 heatsinks the same ones HLG uses on the 600R and I went with a pair of 240 watt drivers. In a tent, with no CO2, even this is overkill lol! I'm running mine at 400 watts . I just now did a spot check at the top of my plants in the photoperiod tent. High was 1103 low was 810 average was 950PPF! right at the limit of usefulness without CO2.
You have the one like I’m going to get right? Not the scorpion?