What Is RAM?

What Is RAM?

RAM stands for Random Access Memory, and if you've ever opened a lap- or desktop computer, you've seen it. In the image above, you see modern RAM sticks for desktop PCs. They have a sleek casing that functions as a heat spreader. However, unless you're a high-powered overclocker, this is mostly about looks (and making them easier to install.)

Laptops, meanwhile, often have more basic RAM sticks, as space concerns are paramount. Plus, unlike modern PC cases with transparent sides, people rarely see the inside of a laptop. However, you can get laptop RAM (especially for gaming models) with heat spreaders.

How RAM Works

RAM is made up of tiny capacitors and transistors capable of holding an electric charge that represents bits of data, similar to processors and other parts of your computer. This electrical charge needs to be constantly refreshed. If it's not, the capacitors lose their charge very quickly and the data disappears from RAM.

The fact that data can be lost so quickly when the charge is gone is why saving any changed data to the hard drive or SSD is so important. It's also why so many programs have autosave features or cache unsaved changes in the case of an unexpected shutdown.

Forensic specialists can retrieve data from RAM under special circumstances. However, most of the time, once you're done with a file or your computer shuts down, the information in RAM is gone.

What Is DDR?

The most common form of RAM currently used is DDR4. It's the fourth version of Double Data Rate Synchronous Dynamic Random-Access Memory (DDR SDRAM). "Double data rate" means data can be transferred twice per clock cycle, as opposed to just once. Effectively, it means you double the memory bandwidth, and also refers to how quickly data can be moved into and out of RAM.

Prior to DDR4, computers were using (surprise, surprise!) DDR3. It's not uncommon for computers to still be rocking DDR3 RAM. DDR4 came out in late 2014, and it didn't become the most common type of RAM until a few years later.

RAM sticks are "keyed" to prevent people from mixing and matching different generations of it that are incompatible. If you look at the RAM stick shown above, for example, you'll see a small divot in the bottom row. On DDR4, that divot is in a different place, so that (along with other differences) makes it impossible to put a DDR3 stick into a DDR4 slot.

RAM also comes in two types: DIMM and SODIMM. DIMM is used in desktop tower PCs and servers, while SODIMM is used in smaller devices, like laptops and compact desktops. Some premade computers (especially laptops) also have RAM modules directly soldered to the motherboard. When this is the case, there are no RAM sticks, which makes upgrading impractical.