Oh dear. Did you update the BIOS before installing the new CPU?
The symptoms you describe are classic signs of overheating and - many years ago - I cooked a CPU by incorrectly mounting the cooler; did you remove the film from the bottom of the cooler? As for the video output, try resetting the CMOS by removing the battery for 30 seconds. If you have the equipment you might check the battery's charge and replace it if it is under 3.1V. Something else to check is the 2400G - check if there are bent pins.
The symptoms you describe are classic signs of overheating and - many years ago - I cooked a CPU by incorrectly mounting the cooler; did you remove the film from the bottom of the cooler? As for the video output, try resetting the CMOS by removing the battery for 30 seconds. If you have the equipment you might check the battery's charge and replace it if it is under 3.1V. Something else to check is the 2400G - check if there are bent pins.