By not starting do you mean being able to boot into windows? because running memory tests, unless they were ran on a different machine makes it sound as if you got it to start, just not boot into windows.
If it does NOT start at all, check the power cable to your CPU, and make sure when you go to boot it up all cables are attached properly and firmly..
I know for me when either the CPU fan died, or wasn't connected mine would not start..
