Not different types per se, but you may be able to put different speeds.
Type would be like DDR Sdram
or DDR2 Sdram for example.
Speed is a slang term for Frequency Rate.
What frequency rate does the ram memory
module (Stick) operate at.
Example: DDR2 Sdram that has a frequency rate
of 667MHz. (PC2-5300) MHz stands for MegaHertz.
Mega = approximately 1
Million. Hertz stands for Cycles per Second.
The above ram memory module
operates at 667 Million Cycles per Second.
If you install two ram
modules that have a different frequency rate, all the ram memory
installed will operate at the slower frequency rate.
computer will support more than just one frequency rate)
Have a computer
in mind, or is this just a generic question? A what if?
Reply to your recent comment:
If this is in relation to two different manufactures of your ram memory, it shouldn't be a problem.
Where you may get into trouble in this area, is if one ram memory module (Stick) is generic, or low budget, and one ram memory module is a high performance gamer ram memory.
Without knowing the exact manufacturer of your computer, plus the Model name of it, and also knowing the information you have about your ram memory 'sticks', the following information is just generic, or general information.
High performance ram memory may use a higher voltage. Not always, but a good portion of the time.
High performance ram may also use a faster set of ram timings.
It may also have high density DRAM chips, and the chip configuration may be setup differently.
(The black rectangular modules you see on the side of a ram memory 'stick', are DRAM chips)
To explain so far;
SDR Sdram was the typical ram memory for years after SIMM ram memory.
SDR stands for Single Data rate.
Commonly just referred to as Sdram, but in actuality that is erroneous.
(Sdram stands for Synchronous Dynamic Random Access Memory)
Then came DDR Sdram.
Double Data Rate Sdram.
Then DDR2 SDram.
Double Data Rate 2 Sdram.
Then DDR3 Sdram.
Double Data Rate 3 Sdram.
(Anything you see on a Wikipedia page that is in blue, is a link to more information.
To further illustrate this,
SDR Sdram specifications were all over the place. What was considered to be a standard for one manufacturer, differed for another manufacturer.
The JEDEC organization was formed.
JEDEC sets the standards for ram memory from DDR Sdram on up.
Voltage for DDR Sdram is 2.5 volts
DDR2 is 1.8 Volts
DDR3 is 1.5 Volts.
Ram manufacturers found that by upping the voltage requirement on high performance ram, the ram could perform, better.
Not true in all cases, as there is high performance ram that operates at the JEDEC standard.
Ram timings were also varied.
Also the chip configuration
Plus the density of the DRAM chip.
Unless it is a really cheap, generic ram module, (Stick), there will be a manufacturers code on the side.
With this code I can tell you the specifications of that ram module.
I can also explain