Ok. So if you take a single RAM module and install only it into the bottom white RAM slot, your system boots normally, but if you shut down your system, and move that RAM module to the bottom light blue slot, when you attempt to boot your system then, you get nothing.
When you install both RAM modules, you're installing them only in the White RAM slots, correct?
If this is correct then it's a motherboard issue and you should have it replaced as RAM slots three and four (the light blue ones) are not working.
-Wolf sends