data being transferred 64 bits at a time
fastest DDR3 1600MT/s -> 64bit x 1600.000.000 /sec = 102.400.000.000 = 100Gbit/s becomes 200Gbit in dual channel mode (in theory)
DDR4 SDRAM, an abbreviation for double data rate fourth generation synchronous dynamic random-access memory
The top DDR4 bus speed will be 3,200 MHz, compared to DDR3's 2,400 MHz, and it will support data transfer rates of up to 3.2 billion transfers per second
If one transfer contains 64 bit -> 3.200.000.000 x 64 = 204.800.000.000 = 200 Gbit/s becomes 400Gbit/s in dual channel mode. (+100% in theory +17% in best practice)
dual channel / single channel:
Anyone doing serious simulation (CFD, parametric analysis) will heavily benefit from dual-channel configurations (~17.7% advantage). Users who push a lot of copy tasks through memory will also theoretically see benefits, depending on what software is controlling the tasking. Video editors and professionals will see noteworthy advantages in stream (RAM) previews and will see marginal advantages in render time.
If you're on a budget or an ultra-budget and are trying to spare every $5 or $10 you can, then perhaps grab a single stick of RAM. It feels so wrong saying that, but we have to trust the results of this test, and the results say that it simply doesn't matter for those types of users.
Most experts believe that DDR4 is the last generation of DDR DRAM that will be made. A few other types of non-volatile memory that can retain data, such as phase-change memory, MRAM (magneto-resistive RAM), and RRAM (resistive RAM), are under development and look promising.
server (ECC) Error-correcting code memory (ECC memory)
ECC is not the end -- Fully Buffered a.o. also exist
Generally this means server or workstation class boards and Xeon or Opteron CPUs.