Will it be over kill?tsl2000 sf 4000=740watt in 4x4 tent

This depends on hours of light -- more specifically whether you grow autoflowers or photoperiod plants. If you grow photoperiods you should always figure out what is needed for 12 hours of light, which is obviously 150% more than you need over 18 hours to provide same amount of DLI (daily light integral). 30-35 watts per square foot is about all you need for any decent LED light. If you add c02 (1200ppm? 1300ppm?) and control temp/rh you might be able to give up to 25-33% more and realize a little less than that in increases to growth rate and yield. a better way than using watts is working backward from a target DLI. 35-40 is a good range to shoot for with ambient co2. 2x4 = 8sq ft / 10.76 = call it .75m^2 4x4 = 16 / 10.76 = call it 1.5m^2 To reach 35-40 DLI you need 800-925 PPFD over 12 hours. Let's go with 900 and that's 38.9 DLI. 900 ppfd * .75m^2 = 675 umol/s needed to hit 38.9DLI in this area over 12 hours A light with 675 umol/s that properly distributes that light over a 4x2 space (rectangular shape would be better and bars or strips better than quantum boards) TSL 2000 give 780umol/s. This is very well-matched for a 4x2. 900 ppfd * 1.5m^2 = 1350 umol/s needed to hit 38.9DLI in this area over 12 hours 780umol/s from tsl 2000 and 1217 umol/s from the SF4000. You have roughyl 2000 umol/s. At normal distances, you need about 70% of power from those 2 lights -- not saying both should be 70% but should average out that way. The SF4000 is slightly more efficient and can shave off a few watts more, so the tsl2000 may need a few more, proportionally to 450w vx 300w units, and you'd also have to consider shape of light frame and resulting distribution of light differences... plus you got overlap between to take advantage of. The SF4000 alone is nearly enough, but you may find benefit in adding more. Running these lights at lower wattage will increase efficacy and extend life of unit. Less heat will be produced per watt used, too. They would absolutely combine to better wall-to-wall coverage, too. 68-72% at normal hanging distances for 12 hours. If running autos, it is proportional to hours of operation. Over 18 hours you need 2/3rds of the above calculated umol/s needs per your 2x4 and 4x4. Definitely don't need both lights if running autos in 4x4. Running that low (2/3rds of roughly 70%) has potential pitfalls in regard to how the driver and diodes operate, but not necessarily, either.. the diodes are not tested in that context by manufacturer. Some drivers operate at lower percentages better than others, too. It would still be better coverage, less heat on diodes and maybe not as much saved in efficacy mostly depending on the driver, if you did use both lights. Without rounding included above, it's 44.6% power if using the 2 different lights over 18 hours at normal hanging distance from canopy. As with the photos, this isn't necessarily evenly distributed betwen both lights. efficacy of lights will shift it a bit. In both situations, this is just a ballpark idea. You start there knowing it won't cause major damage nor be too little light. Minor adjustments will be necessary. Caveat -- more power, more wasteful from a bit further away (there are limits to this) will have a better penetration of light with higher DLI at deeper points in canopy, all other factors the same (specifically 35-40DLI at canopy level). Mathematical certainty, but the gains to lower buds may not warrant the extra cost in watts.