The CD cable is probably loose - the CPU heatsink too.
PSUs that come with the case are usually very bad.
Check all cables/connections again.
Make sure the CPU heatsink isn't loose. If it is you have to reapply thermal paste.
Check the standoffs between the case and the mobo so you don't have a short circuit.
The standoffs must match the mounting holes on the mobo - no more, no less.
Maybe a good idea to try this:
How to Bench Test Your System