Ok another question or two if you don't mind
Can I run these boards up to 240w safely? Will require heatsinking?
I was thinking of running 2 boards per 480 dimmable driver
3 sets of 2 across 4x8 feet foot print
Maxed out at 240 each board I could push 1440 watts?
Is this feasible?
I used a 3mm alusheet for 250w fotops. And a fair bit higher hanging. I wouldnt recomend 250 w on their own, especially since you want ambient at +80F.
I wouldnt run the boards that hard. It only makes the coverage less even and you have to raise the lights. Ive been thru this discussion before; rather than focusing on how many watts you want id focus on the form factor. Make sure your boards literally covers the whole cannopy, with no more than about 6 inches between the boards and run the boards at around 150w each. Anything underneath board is going to flower like a mf-er. If you want more light on your cannopy you can just lower the light. You wont need that extra wattage if you make your fixture right. When you turn these boards up higher they tend to hotspot a bit.
We tested 3 Fotops lm301b at 250 w each against 5 fotops lm561c at 150w each; same wattage and area. The 5 board fixture won; not only in yield but also finished faster, faster to fade. The 5 board could also be kept closer to cannopy.
The higher efficiency of the lm301b should compensate for the 3 board fixture being run a bit harder so the light output should be similar between the 2. But the way how distribution worked out the softer run board won anyway. It was the standout fixture of many. May be noted that we work in a open space so no reflective walls which means a lower hanging fixture has some advantage.
In your case, wanting to add more wattage and maybe wanting some control of the situation: id go for 3 boards per 4x4 lengthwise, and one board across in between on a separate driver, maybe a hlg185. If you want better control over evenness of light could group the 4 side boards together on a hlg600 and the 2 middle boards on a hlg320. That way you can dim and dial in, you get some extra wattage with an extra 200w and you make the fixture go literally from edge to edge of your grow space.