The processor has to take the data and instructions for it to function. However, the rates at which it works, the memory of which takes the data and instructions must be flash. Or, what is the same, ultracara. For this reason, we have created different hierarchical levels of memory.
The fastest and closest to the processor cache, with levels 1, 2 and 3. The L1 is up flash and expensive, and therefore does not exceed a few tens of kilobytes. Sandy Bridge is 64 Kbytes divided into 32 Kbytes for data and 32 for instructions. The level two cache, L2, and becomes more than 100 Kbytes, with up to 256 or 512 Kbytes. The Level 3 or L3 unfolds with several "megas" up to 16 Mbytes. These three levels are integrated in the processor, while the next, RAM, is out, as memory modules.
And finally, the slower cheaper memory but also corresponds to the hard drives, optical drives and Flash memory. These systems are just a support for loading data into RAM. And is that a hard drive can not run anything directly; just loaded into RAM.
The processor first searches its records, then the L1 cache, then the L2, L3 and finally, in RAM. Anything having to go for a data memory means slow down the operation, the more the higher is the data in the memory hierarchy.
Today, memory is DDR3 par excellence. After a long transition, also prompted by integrating memory controllers on processors, DDR2 is alone for old computers, while DDR3 has been expanding both laptops and desktops and netbooks. The fall in prices has been remarkable too, with bargains of up to 10 euros per Gbyte or less.
For extreme memory speeds can reach up to 60 euros per Gbyte, for memories DDR3-2.300. They are positioned as solutions at the end of overclocking performance professionals. Typically will work in speeds between DDR3-1.333 and DDR3-2.000. What is clear is that today having 8 Gbytes of RAM is not a luxury, not even on laptops, where 4 Gbytes on a 1,333 SODIMM module cost around 30 euros.
But these differences in prices are not justified by performance tests, at least for the vast majority of users. In fact, you may find prices of less than 7 euros per gigabyte. Curiously, for SSD price per Gbyte is around 2 euros.
