Consider going with more than 8 GB of RAM I would go with 16 GB if you want better performance working on large items or running multiple apps concurrently. Very low operating voltages, to help significantly reduce the power consumption and extend the usable duration of battery-powered devices. DDR full name is DDR SDRAM (Double Data Rate Synchronous Dynamic Random-Access Memory). It is a main PC system memory.

Q1: Does the number of RAM chips on the module influences the memory speed, reliability, price, physical size of the module? Compatibility is generally not an issue in most cases. But you should go through the motherboard manufacturer's guide of supported RAM modules just to make sure if they are compatible or not.Built-in mechanisms such as DQ shielding, self-calibration, and fly-by topology for enhanced signal control. Increasingly dense fabrication (such as the latest 20-nm DDR3), minimizing the number of chips going into the end product and reclaiming board space that previous-generation chips would otherwise occupy.

Please note we fit 1.35V memory into our G750s. New Haswell CPUs require this and using 1.5V memory can cause problems along the lines of: Operate at voltages as low as 1.2V while enabling nearly twice the bandwidth of DDR3 with upcoming DDR4 memory. Generally you can mix 1Rx8 and 2Rx8, as well, though mixing different kinds of RAM sometimes prevents interleaving (i.e., it might be a tad slower). Energy efficiency can translate into big cost savings for server and desktop environments, long battery life for notebook users, and small carbon footprints. Samsung Computing DRAM solutions boost competitiveness with features enabling you to:

Samsung's expertise in semiconductor memory and experience in delivering next-generation memory technologies advances the design of devices and applications such as ultrathin laptops with extended battery life. Our latest-generation Computing DRAM provides an outstanding combination of speed and efficiency. Dedicated on-board power-management features help reduce power consumption during idle memory cycles. and 2R refer to the number of memory ranks on the module. Dual-rank (2R) modules appear to the system as if two memory modules were inserted in that memory channel, which may cause compatibility issues if you have multiple such modules on the same channel. PC3L can generally replace PC3, but not vice-versa. PC3L is DDR3 RAM spec'd to run at 1.35v, but is generally also fine at 1.5v. PC3 is spec'd to run at 1.5v; it might not work at 1.35v. My work station circa 2011 takes ECC "E" (unbuffered at the time) and my server circa 2006 takes ECC "F" or fully buffered, which then for a time was labeled "R". It just depends on the times.

Voltage drop over the years is because of power saving. Any digital chip power consumed is directly proportional to frequency and voltage squared.PC3 is standard voltage (1.5 V) DDR3 memory, while PC3L is DDR3 L low-voltage (1.35 V) memory. Newer Intel processors (since fourth-generation Haswell) require DDR3L memory; regular DDR3 modules are out of specification for these processors and can cause the system to fail: The right memory solution can be one of your most important competitive advantages. Samsung leads the industry with cutting-edge DRAM technology, including DDR2, DDR3-and soon, DDR4-to heighten the success of your designs. Leverage Samsung's fastest and highest performance DDR3 memory today with a dual-channel, 128-bit memory module to enable a throughput of more than 25.6GB/s. As @davidschwartz pointed out in the comments, the "R" memory is registered which "means it has additional buffers". Sometimes registered memory is called buffered memory.

There are also x4 and x16 DDR modules. Their DDR modules has to hold 16 and 4 of physical RAM chips soldered per 1 rank respectively (to become a 64 bit wide memory). So, if your system came with PC3L then it probably requires it, so don't try to replace it with PC3. But if your system came with PC3 then you can probably replace it with either PC3 or PC3L. x8 (for example PC3 1Rx8) means that physical memory chips on the DDR module/ PCB holds 8 bit long memory. DDR memory is always accessed in 64 bits wide data by the system (72 bits with ECC - error correction code). x8 DDR module has to hold 8 of physical RAM chips soldered in serial per 1 rank (to become a 64 bit wide memory). 9 physical chips for DDR with ECC. Respectively 2 ranks of DDR module has to hold 16 RAM chips (18 with ECC), 4 ranks of DDR module has to hold 32 RAM chips (36 with ECC).

Conditions

Lets make everything clear about DDR RAM. Please, help me to finish all information about DDR3 RAM. And please, correct me if I am wrong. Coming to the PC3 and PC3L part, PC3 RAMs requires an operating voltage of 1.5V whereas PC3L requires an operating voltage of 1.35V. The 'L' in PC3L signifies Low Voltage. So using PC3 RAM in a PC3L RAM slot will not provide it sufficient voltage and it will fail to operate. On the other hand using a PC3L RAM in a PC3 RAM slot may damage it due to overvoltage. So PC3 and PC3L RAMs are not compatible with each other.