What Is RAM? A Basic Definition

Patriot Viper 4 DDR4-3400 16GB RAMPatriot Viper 4 DDR4-3400 16GB RAMRAM stands for random access memory. This is where a PC stores data before it’s processed. A RAM DIMM (Dual Insert Memory Module) is made of up memory chips that a PC can write (and rewrite) rapidly. RAM is a form of volatile memory, which means that it only holds onto data while the chip is powered and erases everything when you shut down. RAM is measured in gigabytes (GB).

What amount of RAM do you need? For most, including gamers and those who do mainstream productivity, 16GB will do. But if you’re a heavy multi-tasker or power user, you may want 32GB of RAM. If your computer ever uses up all of its physical RAM, it can use part of a storage drive as much-slower "virtual memory."

When people talk about RAM in a PC, they are most likely referring to DDR SDRAM (Double Data Rate Synchronous Dynamic RAM), which is usually found on DIMM slots on the motherboard. There have been four generations of DDR memory with the latest (and fastest, best performing and with the largest amount of memory) being DDR4. Most modern PCs and motherboards require DDR4, but older systems may need DDR3 or even DDR2.

In addition to SDRAM, computers use SRAM (static RAM) for the CPU's on-board cache. On the other hand, GPUs (aka graphics cards aka video cards) use GDDR SDRAM (Graphics Double Data Rate Synchronous Dynamic RAM).

When looking at RAM product names, you’ll see the vendor name, followed by the product’s branding, then the RAM type and, finally, a four-digit number. That four-digit number tells you how many mega transfers (1,000,000 data transfers) the RAM can do in one second, the higher the better. For example, the Super Talent Project X DDR4-3000 16GB RAM can conduct 3,000 mega transfers in one second, or 3,000MT/sec.

This article is part of the Tom's Hardware Glossary.

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