Well, the only thing that hit me off as being weird when I looked up the board was this:
Memory Standard DDR2 667
This suggests to me that it doesn't fully support the DDR2 800mhz RAM you tried to place in it, and is the only reason I can think of as to why it won't boot.
That said, it should just be able to run it at a slower speed, and shouldn't cause that much of a problem.
Go into the BIOS (Usually del at bootup, though you may have to press it multiple times to make sure it goes to it)
Here, look for somewhere about memory, and look for a memory voltage setting if its unlocked to change.
It could be possible your motherboard isn't giving the RAM enough voltage to run stabily.
If so, change what is says to 2.0v as a safe limit, and then Save And Exit, by navigating through the menu's.
Try booting again