Pc Doesn’t start after adding a new RAM

Hey there..
i have an ASUS motherboard with DDR 2 ram..
i recently bought a 1 GB DDR2 ram..
My problem is..that when i put the ram in the cabinet …
my CPU starts but the no display comes…
this problem fades away as soon as i remove that RAM..
just for info…in my old RAM ..there is something written as “DDR2 800” and its quite short in height..
whereas..the new one is just the opposite with these written words “DDR@ 667(5) 1gx8”..
Please help…