One user called me today about his Dimension E510 cannot boot up. The system just beeped and nothing happened on the screen. The diagnostic lights 3 and 4 were both on solid green. It’s a typical case of hardware failure. Dell has pretty good documentations about how to determine the cause using the diagnostic lights.
A quick googling of “dimension e510 diagnostic lights” pointed me to the service manual of E510 on Dell’s support site. According to the manual, this is an error caused by RAM. I removed one of the RAM modules and the system booted up normally. The problem RAM module was purchased through some 3rd party vendor to save money. This is not the first time that we ran into problems with cheap RAM modules. I guess I will buy better and reliable components from now on to save me troubles.