I wanted to upgrade system memory in my PC from 4GB to 16GB and got puzzled by the terminologies followed - e.g. DDR3-1333, PC3-12800 by the memory manufacturers.
DDR memory specifications follow DDR-xxx/PC-YYYY classification.
After searching on Google for few seconds, I realized that both the ways refer to memory timings only.
The first number, xxx, indicates the maximum clock speed that the memory chips supports-e.g. DDR-400 memory work at 400 MHz, DDR2-800 can work up to 800 MHz, and DDR3-1333 can work up to 1,333 MHz. It is to be noted that this is not the real clock speed of the memory and the real clock of the DDR, DDR2, and DDR3 memories is usually half of the labeled clock speed.
The second number indicates the maximum theoretical transfer rate that the memory reaches, in MB/s- e.g. DDR-400 memory transfer data at 3,200 MB/s, and are labeled as PC-3200. The DDR2-800 memory transfers data at 6,400 MB/s and are labeled as PC2-6400. Where-as, DDR3-1333 memory can transfer data at 10,664 MB/s and are labeled as PC3-10600 or PC3-10666. The number “2” or “3” after “DDR” or “PC” indicates that we are talking about a DDR2 or DDR3 memory, not DDR.
Maximum memory transfer rate (MB/second) = clock speed (in MHz) * 8.
i.e.
http://www.hardwaresecrets.com/article/understanding-ram-timings/26
DDR memory specifications follow DDR-xxx/PC-YYYY classification.
After searching on Google for few seconds, I realized that both the ways refer to memory timings only.
The first number, xxx, indicates the maximum clock speed that the memory chips supports-e.g. DDR-400 memory work at 400 MHz, DDR2-800 can work up to 800 MHz, and DDR3-1333 can work up to 1,333 MHz. It is to be noted that this is not the real clock speed of the memory and the real clock of the DDR, DDR2, and DDR3 memories is usually half of the labeled clock speed.
The second number indicates the maximum theoretical transfer rate that the memory reaches, in MB/s- e.g. DDR-400 memory transfer data at 3,200 MB/s, and are labeled as PC-3200. The DDR2-800 memory transfers data at 6,400 MB/s and are labeled as PC2-6400. Where-as, DDR3-1333 memory can transfer data at 10,664 MB/s and are labeled as PC3-10600 or PC3-10666. The number “2” or “3” after “DDR” or “PC” indicates that we are talking about a DDR2 or DDR3 memory, not DDR.
Maximum memory transfer rate (MB/second) = clock speed (in MHz) * 8.
i.e.
- 1066 MHz = PC3-8500 8500 MB/s
- 1333 MHz = PC3-10600 10600 MB/s
- 1600 MHz = PC3-12800 12800 MB/s
http://www.hardwaresecrets.com/article/understanding-ram-timings/26
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