+1 for Lugia's post.
The first thing I'd want to find out is if I had a dead or dying module that's tripping my power. Your power supply and case may not be the culprit. They may be doing what they're supposed to.
Also, depending on your country's power set-up... did you check any fuses in the system?
You're going to have to check your modules one or two at a time. Start with the oscillators and work your way down your typical signal flow. Once you have all of your oscillators checked, then go with the VCAs, then filters, and then finally everything else. Let's hope you don't have any bad modules.
The specs for the 6U are as follows:
5HP power supply delivers 1600mA +12V output, 1600mA -12V output and 900mA +5V output
Do the math on each one of your modules as Modular Grid isn't 100% reliable at calculating your power needs.