Understanding Computer Memory - Part 3

DDR3 RAM is much the same as DDR2. The clock speed of the RAM module is rated at twice the modules actual speed. For instance, I am running DDR3-1066, which is 1066MHz. Divide this by 2 and you get 533MHz as the actual clock speed. Remember, You are doubling this clock ratio as before with DDR2. If you download SIW for windows (we provide a free link on our site), you can see under the “Memory” listing where it shows your DDR specification, actual clock speed in MHz, and your PC, PC2, or PC3 designation. There is a free version of this software here: gtopala.com, or you can get the paid for version with additional features. Anyway, DDR3 raises the bar from DDR2 by supplying significantly higher initial clock speeds than its predecessor, and the modules consist of a 240 Pin configuration as before with DDR2, except that the notch to fit the module in place is different since these memory types are not backwards compatible in any way with DDR2. Both Types use 1.8 Volt Power configurations, while DDR uses 2.5 Volts. As said before, less power means less heat, which means less oxidation, and longer lasting electronic components. DDR3 also has a PC designation just as DDR2 did. For instance, PC3-10600 means 10,600MB/s, divide this by 8 to get the DDR3 Specification, which would be 10,600 divided by 8 = 1325 (always labeled 1333 on RAM cartridges). The PC designation measures maximum throughput, while the DDR3 designation measures clock rate.

There are a number of DDR3 (PC3) designations you will come across:

DDR3-1066, 1333, 1600, 1866, 2000, etc PC3-10600, 10666, 12800, 15000, 16000, 8500, etc.

Keep in mind, Some DDR2 and DDR3 memory controllers on motherboards will only work with a RAM module that is rated for its exact speed! I recently came across a Compaq laptop I was repairing when I realized it had bad RAM. All I had was DDR2-800 laying around, but the controller used DDR2-667. I tried installing it and realized it wouldn’t work. Some memory controllers have the ability to work at multiples of speeds. For instance, my Toshiba Satellite supports both DDR3-1066 and DDR3-1333, and some memory modules also support multiple speeds, something that Kingston ( a pioneer in the RAM industry) is famous for. Ram modules usually tend to have either DDR2, DDR3, or PC2, PC3, designations printed on them. You need to know how to read these data rates, not just for the exam, but because when you go to purchase RAM, different manufacturers have their hardware labeled differently. If you needed DDR3 1333 RAM, yet all the modules on the store shelf were rated with PC designations, and you didn’t know how to interpret them, what would you do?

Continue To Part 4 (RAM)