All RAM isn’t the same and DDR3 and DDR4 can’t be used interchangeably. You can’t insert a DDR3 RAM stick into a DDR4 slot because it’s not backward-compatible.
The stick won’t fit into the slot and, even if you did get it wedged in there somehow, your motherboard won’t recognize the format. Only use the version of RAM that your motherboard supports to make sure you don’t break anything.
What Happens if You Put DDR3 in a DDR4 Slot?
Firstly, I’d be surprised if you managed to get your DDR3 RAM into your DDR4 slot in the first place. The two types of sticks don’t look exactly the same and don’t fit into the same slots.
DDR4 has more pins with 288 compared to DDR3 with 240 pins. The RAM sticks also have a small notch among the pins where they fit into a corresponding wedge in the slot on the motherboard. These are also known as keys, at in the same place. The notch on DDR3 sticks is closer to the side of the stick while it’s more in the middle with DDR4.
In addition to all of that, DDR4 is also slightly curved, with the middle sticking out slightly more to one side than the ends. The DDR4 slot in your motherboard is similarly shaped to accommodate that curve. So no matter which way you look at it, DDR3 RAM can’t fit into a DDR4 slot or vice versa.
Even if you somehow managed to get it in there, motherboards generally aren’t made to recognize both the DDR3 and DDR4 formats. So you would have shoved your RAM stick into a slot where it doesn’t fit with no effect. Besides physically harming your motherboard and RAM, you could also further damage your hardware if you tried to turn your computer on.
Can a Motherboard Support DDR3 and DDR4 RAM at the Same Time?
You likely won’t be able to find a motherboard that supports both DDR3 and DDR4. While there are some rare motherboards that support both, most motherboards only work with one or the other. So if you have sticks of both types of RAM lying around, you won’t be able to combine them.
Some of the more well-known combo or dual motherboards that support both are:
Intel Skylake LGA1551
Biostar Hi-Fi series H170Z3 and H150Z5
Asrock B150M Combo-G
Instead of giving your setup a boost in performance in any sense of the word, however, there’s no real benefit to using both types of RAM. At least, that I can see. Because motherboards that support both, like Biostar’s Hi-Fi series, typically make you switch between one or the other.
That means you aren’t really using both at the same time. It greatly diminishes your capabilities compared to just using more RAM of the same type. Using 2 sticks of DDR3 or 2 sticks of DDR4 is much less efficient than just using 4 sticks of either. Plus since they’re so rare, the price tag of these motherboards just doesn’t justify not buying more of the same RAM instead.
Check your motherboard’s store page or the model’s page on the manufacturer’s website to see which version it supports. The website should clearly state whether the motherboard supports either DDR3 or DDR4 RAM. You don’t have to use the same RAM size since it doesn’t matter if you combine 8Gb and 16Gb sticks, as long as they’re the same type of RAM.
What’s the Difference Between DDR3 and DDR4 RAM?
Random Access Memory (RAM) is your computer’s short-term memory cache. Your RAM is responsible for storing information that your CPU can quickly access whenever it needs for the program you’re currently using. It takes much longer for CPUs to read or relay information to and from your hard drives but they have a lot more space.
Like I mentioned earlier, DDR3 and DDR4 RAM physically look different. That’s not the only difference, however. DDR4 is the next generation of DDR memory which uses an updated interface protocol that allows larger bandwidth and a smaller latency difference. Essentially, that means DDR4 can read and write information faster along with having a larger maximum storage capacity.