You do not have DDR4. You have DDR3.
"SODIMM" is "Slim Outline Dual In-line Memory Module". The difference between laptop memory and desktop memory is that the "Slim Outline" (SO) part is eliminated. So, if you're getting laptop memory, it must be "SO-DIMM", not "DIMM".
Ignore anything about "DRAM", "SDRAM", "SRAM", etc. Websites may typo it, but there's only one type of RAM currently in wide use in the market called "SDRAM"; Synchronous Dynamic Random Access Memory. If a website says "DRAM", they are omitting the "S", but really they are talking about the same exact thing. This tends to happen when the same thing has been used for such a long time that people forget what it's actually called.
So you have
- Slim Outline (laptop memory)
- Dual In-line Memory Module (the memory physical layout used in the past ~15 to 20 years)
- Synchronous Dynamic RAM (*the internal/electrical architecture used in all PCs in the past ~15 to 20 years)
- Double Data Rate version 3 (DDR3) (the speed generation of the RAM. DDR2 is actually still somewhat modern, and in use on older systems, but DDR3 is the most commonly used. DDR4 is very new and is not commercially available on consumer systems.)
- 800 MHz, which is the multiplied-out standard clock rate of your DDR3.
I knew that you didn't have DDR4 before I even looked up your notebook, because DDR4 SDRAM is just starting to be produced this year, and you can't even buy a CPU/motherboard combo that supports DDR4. DDR4 for extreme high-end desktops should be available with the Haswell Enthusiast series of Intel processors, due out in 2014.
A good search term for shopping would be "x GB SODIMM DDR3-800", replacing "x" with a number, like, 4 or 8, depending on how many gigabytes of RAM you want.
A few notes:
- If you get RAM that does not specifically say SO-DIMM, it will NOT work with your system! The advertisement may also say "laptop memory", but "SO-DIMM" is fine.
- If you get RAM that does not specifically say "DDR3" or "PC3" followed by a number, it will NOT work with your system! "DDR3-####" and "PC3-####" are two different ways to represent the revision of the DDR spec it's implementing, followed by the MHz (clock rate).
- If you get RAM that is faster than the maximum rated speed your system allows -- in your particular case, 800 MHz -- it may not work, but in most cases it should work.
- If you get RAM that is slower than the maximum rated speed your system allows, it may or may not work, but you should generally avoid this for performance reasons.