Here's something to check into, since you moved all components to a new case.
Any mobo is mounted in a case using items called stand-offs. These usually are little brass items about ¼" long with a threaded shaft out one end and a threaded hole in the other. They are screwed into pre-drilled holes in the backing plate of the case, and then other screws go through holes in the mobo and into the stand-offs. These create an isolation space between the case's back plate and the mobo bottom surface, and provide mechanical support for the mobo. If you look closely at the holes in the mobo (often arranged as three rows of three) you will see little metal "fingers" around each hole. The design intends that the mobo will be grounded to the case via the screws and stand-offs at these mounting holes and via the power supply cables from the PSU, but at NO other place.
Thus, the position of the stand-offs in the case backing plate is important - it MUST be matched to the mobo mounting holes. Sometimes a case arrives with those stand-offs separate in a bag and you MUST install them correctly. Sometimes they are pre-installed in a set of common locations, but there are more holes for them to accommodate other mobo layouts. Ideally, you should have a stand-off under each mobo mounting hole for good support. But MORE IMPORTANTLY you should NEVER have a stand-off under the mobo where there is NO mounting hole. A mis-located stand-off like that can cause a short circuit from a mobo bottom surface trace to the case.
So, re-examine the positions of all your stand-offs and ensure that every one of them matches a mobo mounting hole. To do this you may have to remove the mobo from the case for a careful inspection, then re-install after any adjustments.
One other small mistake I have seen applies only to certain types of fans. SOME fans come with wiring ending in TWO connectors - one wide one to plug into a PSU Molex power output, and another small one to plug into a mobo fan header. These are designed to allow you to use EITHER of those power sources for the fan but NEVER both! So IF you have any fans of that type, ensure that you have plugged in only ONE of those connectors for each fan, and the other is not used.