|You didn't state if any of the RAM modules are properly identified in the POST screens. |
Did this issue happen suddenly or gradually?
You could try cleaning the RAM using a pencil erasure. Try installing the same stick in the same slot 4 or 5 times to clean off any oxidation. I don't hold alot of hope for that though because your problem is system wide.
The PSU may be faulty. Boot into the BIOS screens to PC Health and look at the voltages to see if they are close to what they should be.
Also, examine the motherboard looking for bulging or leaking capacitors.
Have you experienced any power outages or storms recently?