Definition: dynamic RAM

The most common type of computer memory and generally available today in the form of DDR SDRAM (double data rate synchronous dynamic RAM) chips (see SDRAM). Most all volatile memory is dynamic RAM, which uses one transistor and one storage capacitor for each bit. Dynamic RAM is denser and much less costly than "static RAM," a faster counterpart used to speed up processing (see cache).

AI Demand Changed the Game
Perhaps temporarily but due to the enormous demand for memory in AI datacenters, the price of dynamic RAM rose dramatically in early 2026. For example, some DDR5 modules that cost $100 in 2025 were advertised for more than $400 in 2026. See DDR5.

Dynamic RAM Is a Total Loser
Unlike the flash memory chips in SSDs that hold their contents when the power is turned off, both dynamic RAM (DRAM) and static RAM (SRAM) require constant power. See flash memory.

The capacitors in a dynamic RAM chip are electrical storage tanks that do a poor job of holding a charge. They leak, and the memory chip would lose its current state were it not for refresh circuitry that re-energizes the capacitors approximately 15 times each second. That refresh turns off when the power turns off.

A Lot of Bits Today
In 1968, dynamic RAM was patented by IBM, and the first commercial chips came from Intel and Mostek in the early 1970s with a capacity of 1,000 bits. Today, 16GB of dynamic RAM is entry level in most desktop PCs, and that equates to 128 billion bits. Gaming PCs often have four times that much memory, and workstations can have 2TB (16 trillion bits) or more. See static RAM and memory types.

A Dynamic RAM Cell

DRAM cells are very simple. The combination of voltage on the row and column lines charges a capacitor. The only problem is that the capacitors keep losing their charges, and the bits must be read and re-written to the same state several times each second.