RAM – What do those numbers mean

RAM – What do those numbers mean

You might be looking at a new computer, or laptop and see RAM advertised with a series of numbers designed to impress you. Here I will try to explain to the curious what they actually mean. RAM comes in three main flavours, with differentDDR RAM Chip ratings on each of those flavours. The “flavours” being DDR, DDR2, and DDR3. This is fairly jargon intensive but I will do my best to explain this in plain English. You may see RAM advertised as something similar to this “DDR3-1333” or “PC3-10600” which are actually identical, but using different naming conventions. Technically the DDR naming convention refers to the actual chips, while the PC3 refers to the “module” of chips. You plug a module into the computer, which is made up of a number of chips (often 8). None of this really matters to consumers though.

DDR stands for “double data rate” which essentially means that the RAM transfers two chunks at a time. DDR2 and DDR3 are iterations of the original DDR specifications. Each new iteration is capable of additional data transfer rates. One of the main differences other than speed is that DDR2 and DDR3 require less voltage (hence power) to operate. So, PC2 ram refers to DDR2 and PC3 refers to DDR3 standards. The theoretical maximum data transfer for DDR(1) RAM is 3,200MB/s and DDR3 increases all the way to 12,800MB/s. The reason I mention theoretical is that RAM is limited by the motherboard. So if your motherboard does not support the highest transfer speeds, the RAM will be throttled down in performance. So when you see PC3-10600, the code is telling you that the RAM is DDR3 running at 10,600 MB/s. Now let’s look at the other naming convention.

The other naming convention such as “DDR3-1333” refers to the clock speed of the RAM. The transfer speed is calculated by a simple formula “Maximum Transfer Rate = clock * 8.” So in the example above DDR3-1333, we take the clock speed of 1333 and multiply it by 8, and get a result of 10,664 MB/s which is rounded down to the much simpler 10,600MB/s .