Please update your System Specs
System Info - See Your System Specs
I am mainly interesting in knowing which motherboard you have.
Your post is confusing,
So you have used the NEW power supply, it worked before you changed the RAM.
Now your computer will not boot or turn on? With the new AND old ram?
Later you removed your old power supply ....? When was it in?
Have you tested the new and the old ram with your old power supply?
Please post back with the 2 power supplies you have also