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 in-line Memory Module), or more simply thought of as a RAM stick, is made of up of 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 the PC. RAM memory is measured in gigabytes (GB).

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. On the other hand, GPUs (aka graphics cards aka video cards) use GDDR SDRAM (Graphics Double Data Rate Synchronous Dynamic RAM). Modern RAM offerings all use SDRAM, but sometimes you'll see people and retailers refer to it as "DRAM" anyway.

How much RAM do you need (including for gaming)? 

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."

What is DDR4 and DDR5?

There have been four generations of DDR memory. DDR4 is the most recent. It's the fastest and has the best performance and largest amount of memory, so the best RAM offerings use DDR4. Most modern PCs and the best motherboards require DDR4, but older systems may only support DDR3 or even DDR2.

The race to DDR5 is currently a-go, with vendors like Cadence and Micro planning for production by the end of 2019. However, SK Hynix in November announced that it's the first to develop DDR5 that complies with JEDEC standards. For all the details on DDR5, check out our article, What We Know About DDR5 So Far

What is SRAM?

In addition to SDRAM, computers use SRAM (static RAM) for the CPU's on-board cache.

Understanding RAM Product Names

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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