Every laptop needs some memory (RAM). Without RAM it will not work. RAM stands for random access memory and this explains what it is. It is basically a memory chip made from semiconductors.
Why we need memory at all, well, this is everything to do with the speed. As you know already the processor operates at a blazing speed, and it does not have enough memory inside to store all the data we usually use. The processor has memory inside, but it needs 100 times more of it to be capable of working efficiently.
Though, the processor could work with a hard drive instead of memory. However, this would be a slow laptop and not worth the money we paid for it.
I mentioned earlier that the laptop would not start if there is no RAM. You can try it yourself by taking out all memory modules – the laptop will not start, there will be no image on the screen. This is because BIOS (basic input output system) uses a small bit of memory. It’s the same situation, an instruction set called BIOS must be loaded first to the memory for the processor to work with it.
BIOS is simply a piece of coded firmware that makes all laptop components work.
There are few laptop memory types.
The first one I remember is SDRAM (DIMM). It has been used in the early days when we used to have Intel 386 or Intel 486 ( or AMD K5 or K6) as processors in our laptops.
Then the new memory came out known as DDR. This was a huge upgrade. The memory modules were not compatible with SDRAM, so you needed to upgrade the motherboard to use them.
Then the DDR was upgraded to DDR2. And again, this was a huge improvement in speed. Also, in this case, DDR2 was not compatible with DDR1.
Then, shortly after, the DDR3 came along also with improvement of speed and bigger amounts. However, honestly this time, there was not that much of a huge improvement in speed. DDR3 is also not compatible with DDR2.
DDR4 also succeeded DDR3. This memory is widely used today (in 2018). I also have a laptop with DDR4 and an SSD drive.
RAM markings. You probably need not to know everything except that the first number is memory amount 1GB, PC2 means DDR2 and it can be written DDR2, 666 indicates speed and the last numbers are latency. Do not worry too much about those numbers but if you buy two modules make sure all those numbers are the same, and the manufacturer is the same, i.e. Samsung.
Does it ever fail? The short answer is yes.
Below is an example of a report from memory diagnostic software. It shows this memory module has a few faulty cells. The fault can happen for many reasons. Maybe there is a defect in the chip, maybe the chip has pins not soldered to the PCB (printed circuit board) pads, etc.
In general, RAM is very reliable and this fault shown is rather an exception. The symptoms with this fault can be as follow: laptop freezes randomly, sometimes refuses to start, laptop crashes with a blue screen.
How that report above was generated. This is very simple small software MemTest that writes some information to a memory cell and then reads it, and this is done many times with a many of different data to use all the cell that are there.
The optimal amount of memory is when the laptop does not use the hard drive to store part of memory that supposed to go to RAM. You can sometimes notice that the laptop is slowing down for a considerable time and then after a while get fast again. This is exactly the cause of memory shortage.
Different operating systems and different programs need different memory amounts. Windows XP, for example, will work even with one GB (Giga Byte) of RAM.
Windows 7 probably will need 2GB and more.
Windows Vista. Well, better to “upgrade” it to Windows 7. You will be happier.
For Windows 10 4GB of RAM is needed and preferably more.
Memory compatibility. There are a few memory manufacturers out there and with all that ordinary memory laptop would work just fine.
The problems arise when we use two memory modules the same amount and speed but from different manufacturers. Then all the sudden a crash can happen, and you would not know what’s going on.
Here is the explanation. I have here two memory modules that are the same amount and type RRD2 but slightly different in speed.
The PCB looks almost the same with some minor differences. Now the speed of those two modules will be slightly different. Laptops supposed to be fine with these differences but in reality, still something goes wrong, and those memory modules can’t work properly together. This may be due to the high speeds that the memory is operated; no one knows for sure.