OK, more info please.
1. I assume you did connect a 4-pin Molex power output from the PSU into the WHITE connector in your photo to provide power to the fans. And that you have connected the main 24-pin cable to the mobo. AND that you also have connected the require power cable from the PSU to the mob socket that feeds the CPU chip. All right so far?
2. So what does happen? How are you trying to start ip - push the front panel power button? Then does NOTHING happen, or do the fans start up very briefly, or what?
Consider this. In every case there are small units called stand-offs under the mobo that support the mobo away from the case's rear panel. These MUST match up exactly with where the mounting holes of the mobo are. You have changed to a new case. That case MAY have arrived with no stand-offs installed, requiring you to do that. OR it may have had then installed, but not necessarily on all the right spots. IF you know all about this, check them. If not, post back here for details. A misplaced stand-off (or none) can cause a short circuit that prevent normal operation.