What is a LP DDR3 RAM

How to recognize extra economical RAM

Thomas Rau

In the case of processors, economical operation is becoming more and more important - but not only for them. The main memory can also help the PC to use less power.

EnlargeEconomical memory: An LPDDR3 is found in many tablets and smartphones. As a result, the mobile devices not only consume less electricity, but can also be built very flat.

Current notebooks usually work with a DDR3 memory. It differs from the DDR3 in PCs only in the design of the RAM modules: Notebook memories sit on SO-DIMMs with 204 contacts, while the RAM bars for the PC have 240 pins. Both work with an operating voltage of 1.5 volts.

This is why the official DDR3L standard with a lower voltage of 1.35 volts has existed since 2010. It sits on the same modules as DDR3. The chipset and the BIOS must support this voltage so that the RAM runs with it. In most cases, DDR3L can also work with the usual 1.5 volts - but then you do not have a saving effect. DDR3L memories are also well suited for overclocking experiments: They run more stably at higher voltage, which enables a higher clock rate or shorter latency times.

Alternatively: maxing out RAM with aggressive timing

In notebooks, the savings effect from DDR3L memory is only slight. With tablets and smartphones, however, every milliwatt of energy saved counts. That is why mobile devices often rely on the even more economical LP-DDR3 (Low-Power DDR), which uses an operating voltage of 1.2 volts. In addition to the low voltage, the low consumption in refresh mode in particular means that LPDDR3 memories hardly put any load on the battery in standby mode. So that the RAM retains its content, it has to be rewritten at regular intervals (refresh): DDR3L needs 15 milliwatts (mW) for this, while LPDDR3 manages with 1 mW.

The most important advantage of the LPDDR3: It takes up less space - for example, the RAM can also be soldered directly onto the processor. This is the only way to make extremely slim ultrabooks, tablets and smartphones possible, but an LPDDR3 is comparatively expensive. That is why it is currently only used in top products such as the iPad Air, the iPhone 5S or the Galaxy S4. Intel's new Haswell mobile platform also supports LPDDR3. This is why the economical memory is used in the Macbook Air 13 from Apple - there already as an LPDDR3-1600, i.e. with the same clock rate as a DDR3. Most tablets and smartphones, on the other hand, have a slower LPDDR2-1067.