DDR versions do not support forward or backward compatibility. So,you cannot use a DDR3 memory stick in a DDR4 slotand vice-versa. Not only this, youcannot mix RAMwith different DDR versions on any motherboard.
DDR3 and DDR4 memory havedifferent numbers of pinsand run on speeds that are poles apart. This also means theRAM operates on different voltages. To prevent users from connecting the wrong stick and slot, thekeying/notch is in a different location.
However, there are some motherboards with DIMM slots that support different DDR versions. Here too, you may only connect aDDR RAM typewith its designated DDR slot.
Physically Not Possible
The notch on the DDR3 stick is slightly on the right side. While for DDR4 slot, it’s near the center. So, you cannot physically install a DDR3 on a DDR4 slot.
Besides keying/notch, there is another physical attribute that restricts users frominstalling DDR3 RAMin a DDR4 slot.
As you may see in the picture, the DDR4 RAM has aslight bulge areaaround the center. To accompany this, the DDR4 slot also has asmall dent. This allows the DDR4 RAM and DDR4 slot to fit in perfectly.
To prevent users from connecting different DDR generations, the notch/key and the small bulge exist. So, if you try to force insert a RAM of a different generation into the slot,the RAM slot,sticks, or theMobo will get damagedand not work later.
The internal architecture of each DDR generation is completely different. Newer DDR generation comes with the latest technology and data transfer mechanism.Older DDR slots are not designed to operate with newer DDR memory modules.
In the same way, DDR3 and DDR4 memory modules are completely different. DDR4 runs at a higher speed of up to5333 MT/sandperformance is much better. While DDR3 is limited to3200 MT/s.
It also has a greater bandwidth andsupports a higher capacity. DDR4 slots are designed to support these specifications.
Here are a couple of other reasons why communication is impossible between DDR4 slots and DDR3.
Mismatched Number of Pins
Both DDR3 and DDR4 communicate to the CPU using the 64-bit wide bus. Even though it uses the same memory bus, how it communicates with the CPU is completely different.
The two DDR types have different numbers of pins and so does the slot. DDR3 has a total of240 pinsfor DIMMand204 for SODIMM. DDR4 has288 for DIMM unitsand260 for SODIMM.
The pins on DDR3RAM is not compatible with motherboard’sDDR4 slot.
Furthermore, each of these pins has a designated task. Some pins are to access the address bus and some access the data bus. The task of each connector pin is different depending on theRAM type.
For a successful communication, the pins on the RAM must connect to the pins on the slot. This is not possible when the total pins are different on the RAM stick and the slot.
Voltage Incompatibility
Another crucial point is the difference in voltage.DDR3 operates on 1.35 and 1.5V(1.35 for DDR3L and 1.5 for DDR3). DDR4, on the other hand, operateson 1.05 and 1.2 V(1.05 for DDR4L, 1.2 for DDR4, and 1.35 when enabled XMP).
Can a Motherboard Run DDR3 and DDR4 Simultaneously?
Manufacturers used to produce motherboards with different generations of DDR slots. Here are a few motherboards that could support two different DDR generations.
One thing to note is that you need to use only one single type of DDR RAM in this motherboard.
Consider you have a DDR3 and a DDR4 RAM stick, and a motherboard with a slot for both. Youcannot boot the systemwith both of these modules installed. The system needs either one or the other to run, not both.
Processors, especially Intel, come with support for two DDR versions. Intel 12th Generation processor supports bothDDR4 and DDR5 RAM. Butmotherboards today do not support multiple DDR versions. And there is quite a good reason for it.
First off, these older motherboards could only usetwo sticks instead of four.
Secondly, manufacturing boards that support both DDR generation means power supply for two types of RAM. So, this would require a separate pin configuration.
Along with this, using four sticks of memory instead of two performs better. So, these boards although they support different RAMs will not have much of a performance benefit.
Memory Modules For DDR4 Motherboard
you may only use aDDR4 memory stick on a motherboard with a DDR4 slot. If you are getting a new RAM,check for writings that say DDR4on the label.
you may find DDR4 RAM in two different form factors. Both these modules will have DDR4 on the label. However, it may not fit in your system.
The label on your RAM should say DIMM or SODIMM. You need toget DIMM DDR4 RAM if you are a desktop user. Forlaptop users, you need to get SODIMM.
Furthermore, I also recommend you consider the maximumRAM frequencyyour system supports whenchoosing a memory module.
Depending on the motherboard,processor used, and OS installed you will alsofind maximum RAM capacity. So, ensure you install RAM below this limit.
