To back up
@L0wbob2017 dimming a cob with a potentiometer isn't the way to do it its not like incandescent bulbs and brings with it a whole bunch of other issues some of which were mentioned, but dimming is typically done one of two ways either current limiting or Pulse Width Modulated control which effectively flashes the led's.
But back to your driver combo unit i presume its one of those ebay generic cobs and tin can ballasts, if so a lot of those aren't actually 100w, might list as such but it all depends on what ballast is paired with them "current x volts = watts", and at 100w they don't last very long.
Second to that you will need adequate cooling especially in a pc case, where in my opinion 100w is way way to much and honestly you wont be able to cool it effectively unless you have external mounted heatsinks and no filtering and even still plants wont be able to get any where near close 4+ inches or they will crisp up.
So saying that if your actually wanting to build a stealth PC case i'll give you some suggestions from my own trial and errors.
First multiple sources of light is the way to go, when running only a couple light sources or less you end up concentrating the light and heat into areas right around your light source, the down side with that is you will create dark areas in your case where things wont grow as well, and also have a cone right under your light source where plants cant go into without being crisped up either due to light intensity and or heat, but typically both, where as with multiple sources everything gets evened out and plants grow a lot more evenly and don't have those cones of burnage.
Wattage wise you probably don't want to go over 50w a sqft, i have and do run above that with my cases which consume 65watts each but thats due to not so efficient ballasts and me being on the upper end of the spectrum for light concentration, 25-40w is a nice range to start and run with.
Now you can run cobs and i have and they work great when under driven, but for the best bang for your buck honestly take a look into dismantling some screw in led light bulbs and mounting the cobs to some heat sinks, Standard cost to outfit a pc case is $10-20 plus heatsinks, Take for example the Philips 8w led bulbs they are 4 for $10, or the bigger 14.5w which are 2 for $12, in a pc case you only really need to run 4 of the 8w ones or 2 of the 14.5w ones, or up to 8 and 4 respectively if your wanting to be on the really high side of the light spectrum, but you will have to deal with the heat.
Which leads us to Heatsinks, old CPU heatsinks are your friends, i've used a lot of the stock intel lga1155/1156 socket heatsinks which you can typically pick up for free to $5 a piece as they are always the first thing chucked aside when building a custom pc, but they work great for smaller wattage cobs, i cut the fans off the stock holders and flip the heatsinks in them giving you a handy mounting bracket.
As for color temperature of your light even though this is contrary to the old thought on it, which is different now but i highly suggest going with lights in the 4-5000k range instead especially in a pc case, the reason being is due to the bluer light your plants wont stretch as much in comparison to the the light of a 2700k source for scientific reasons i wont get into, but in a limited height environment that's a good thing as we want to limit stretch as much as possible, as for difference in yield you wont notice any or it will be fractions of a difference, i've personally always had healthier plants under a cooler spectrum, where as sure buds finish nicer under a redder spectrum for the last couple of weeks of flower, but all that time before hand they are trying to stretch and outgrow your space, so we need to play it to our advantage.
Feel free to ask any questions, and my threads a blab a lot in so i fully understand just looking at the pictures lol.
