Random access memory and data
RAM is cleared after each power cycle.
The power-up value of cells depends on the technology.


Static RAM content is usually random (there is no preference between 0 and 1, but the same chip may present similar patterns after each power-up).
Dynamic RAM has the value corresponding to empty capacitors in the RAM array, which usually corresponds to ones, but there is no guarantee. 
Dynamic RAM can retain data for several seconds when unpowered (very dependant on temperature) : One cannot assume a known state at power-up and recent DRAM (DDR3, DDR4...) need complex initialization sequences where the RAM controller stores and checks some values like FFFF/0000/AAAA/5555, ...)