Oh please do not ruin your nice Rocketfish PWM fans. They appear to be PWM versions of standard Chinese generic fans. As such they will provide a soft air output and not much noise. In my study I found that generic fans are just fine within their limits.
Your main problem is that you are using a Dell motherboard. Every connector is proprietary. You can only use Dell power supplies. On and on.
I have used Dell fans. I clipped off their plugs and replaced them with standard plugs. You will have the opposite problem: adapt standard fan plugs to Dell fan headers. Luckily for you, I just tonight saw this
. Three of these and you can put your PWM fans to work.
But really, it's a shame to waste your money and your energy. You have a fine case. You have fine case fans. It is unclear whether you will be able to control your fans with your Dell mb. Have you looked in your BIOS to see if you can find any controls? Remember, Dell makes their machines for the mainstream consumer, not modders like us.
IMO you'd be better off buying a low-cost Gigabyte motherboard for your CPU. They tend to have flexibility in how they allow for fan control, and you can readily understand their BIOS. Putting your Dell mb in a new case is like pouring old wine in a new skin. Time to move on.