By "keeps trying to" do you mean it comes on, then shuts off right away, only to come on again and shut off, over and over?
First, look at the Motherboard and see if there is any blown capacitors.
Second, test the Power Supply to see if it is still good.
Third, try removing the RAM and using a known good stick of RAM.
Fourth, try removing any cards that are plugged into your PCI or PCI-E slots.
i have tried the power supply and it is fine. Yes I mean it comes on and shuts off right away, i dont even see the Dell screen come on. It's almost like its not getting enough power, im not sure. But like I said the power supply is fine. I will try checking the other three things you suggested though. Thanks alot!