A few things you can try:
1. Clean the MB with air, especially the power supply. You can finish the job with circuit board cleaner.
2. See if Cosmo has anymore Gal replacements for the Pals.
3. Elevate the 3000 by it's feet an inch or so, the bottom gets quite hot.
4. Replace the power supply fan with another 80mm 2/4 wire fan, the stock one runs at 2500RPM, find one that runs faster.
5. Add another fan to the front of the case.
6. Never run a 3000D without it's case for any period of time.
7. Add heatsinks to the hottest running chips. Generally all the chips around the Pal/Gal u202 chips etc, run the hottest.
8. You can remove and clean all the socketed chips and try reseating them.
9. Make sure that you keep the front and back of the system away from a wall.
You don't need to hack the case to let it run cooler,
Good luck..