Many people had this problem but I cannot find the solution. Anyone know? I tried to use different memory, a video card, and even a new power supply. Same results, and I even tried taking the mother board battery out and back in. The computer just will not turn on. Check out my other post in a different section on these forums if you need more specific information (link is below).
Look in the troubleshooting section, and match the color/pattern of your little error lights (1-2-3-4) with the table in the manual.
lol i know it is a late reply but, anyway, i tried that thing you said. the dell information did not help out all (first and last time a buy a dell). it turns out it was the frontal i/o and the motherboard battery the whole time.