First Cob Build

Hi everybody,
I've been lurking this site since the early 2000s but finally signed up so I can ask my own questions, lol.
For my first COB build, I want to set up a flowering light in a 4' x 4' closet space. The closets about 6' x 6', but I want to get a perpetual harvest going with a veg tent and a seedling/clone area. Anyways, I am willing to spend a few hundred, but really want to keep initial costs as low as possible. Marginal differences in efficiency are of no concern to me, but if the savings could be significant within a year's time or less I think it would be worth it.

So far I'm looking at the Bridgelux Gen7 V22 4000K, with 2 x 360W drivers off of a website I will refrain from linking to, and a bunch of CPU coolers with 12v fans. The light would ideally be 4 x 4 COBs total dimensions 36" x 36". I was thinking I could wire 4 groups of CPU coolers, 3 in each group. 3 12v fans in series should be 36v right? Then I could wire two groups of fans on each PSU in parallel to the LED string.

The PSUs I found say this: "Suitable for LED Bar lights, Hard light LED soft lamp strip, LED module DC Power supplies and other fields."
I'm slightly skeptical because they are 20 each, but everything I can gather from them, they seem like they would be compatible.

Any input would be appreciated!

720 watts for a 4x4? overkill in my opinion. hopefully you can dimm them and have some way to supplement co2 for that much light.you might be able to use 200 watts or so less.

Yea, you're right. My math was off on that for sure. I was thinking I needed 100,000 lumens total, but I think I only need about 80,000. I was actually starting to be tempted by the Chinese COBs with integrated AC drivers; for like 2 bucks each, but now I'm rethinking. A lot of trade-offs to consider, and for me the upfront costs are weighing a bit more heavily. I could run 25 of the 50W chinese ones, at half power and do 625W; maybe just the center one at full power since there's an odd number, and I would need groups of 2 in series to chop the voltage in half. I even considered a 3-way switch to toggle a few groupings on or off for different power levels since they can't really be dimmed out efficiently.