Can You Mix RAM Speeds? – Find Out 2022

RAM or computer memory is a key component to a computer build, and a PC will not run without it. The RAM is responsible for communicating with the CPU, and the speed the RAM runs at determines how fast the RAM can send and receive data with the CPU. Mix and matching RAM speeds on paper is possible depending on the motherboard, but it’s seen as bad practice, you should use identical RAM sticks together

In this post, we’re going to go over the effects of mixing and matching RAM of different speeds, and whether it’s worth it. You’ll also find out if mixing RAM with different voltages is possible and whether it’s a good idea. Also, we’re going to discuss whether you can mix RAM modules with different CAS latencies, and what the best RAM speed is for gaming.

Answer: The idea of mixing RAM modules usually occurs when you want to purchase more RAM, but the module you’re currently using isn’t in stock. And in most cases, if the RAM is of the same generation (DDR4 for example), then the RAM sticks should theoretically work together. However, we’re going to find out if mixing RAM speeds is a good idea and the consequences of doing so.

What Is RAM And Why Is It Important?

ram for streaming

RAM or Random Access Memory is a storage device that has to work very fast, usually in the nanoseconds to work and communicate effectively with the CPU. The RAM is a volatile storage device which essentially means it will destroy any data stored when the system shuts off or loses power, this is the opposite of SSDs and HDDs.

The RAM on your computer works closely with the CPU like how the VRAM works closely with the GPU. The speed of the RAM or the clock speed tells you how fast the RAM is able to send and receive information from the CPU. The more RAM you have the less hard the CPU will have to work by processing information from the permanent storage.

The RAM has a few important specifications you need to pay close attention to, especially when attempting to mix and match modules. The main specifications of a RAM module are the RAM Size/Capacity, DDR Generation, Clock speed, and CAS Latency. In this post, we’re going to primarily focus on the Clock speed and also the CAS latency. The DDR generation is also important.

RAM modules are installed onto the motherboard and they usually come in sizes of 4GB, 8GB, and 16GB. The speeds of RAM also vary and differ between generations, but DDR4 RAM speeds come in at 2133MHz, 2400MHz, 2666MHz, and 3200 MHz. The speed of the RAM can also be overclocked within the BIOS to get more out of your system especially when gaming.

What Happens When You Mix DRAM Speeds?

If you happen to come across two different RAM modules of different speeds for example DDR4 2400MHz, and DDR4 2666MHz, pairing them both together will cause the fastest RAM module to run at the same speed as the slower module, so DRR4 2666MHz will run at 2400MHz. They have to be of the same generation for this to work, DDR4 RAM will never work with DDR3 RAM due to hardware and physical incompatibilities.

A similar effect will occur if you run two different RAM modules with different voltages together, the RAM module with the lowest voltage will overvolt to become compatible with the module with the higher voltage rating. It used to be that this would never work together, especially with older motherboards, but now motherboards are getting smarter and allowing things like this to work together.

You can even mix RAM modules that aren’t of the same brands, the system will find a balance between the two modules by overvolting and reducing clock speeds. But mixing and matching RAM isn’t recommended because it can cause instability issues and cause more harm than good. Using identical RAM sticks is far more advantageous because it’ll be far more efficient and stable.

Can You Mix RAM With Different CAS Latencies?

mixing RAM

Mixing and matching RAM modules with different CAS latencies is the same story as mixing RAM with different clock speeds. The system will try to find an equilibrium between the RAM modules usually by raising the latency of the fastest module. While this is all theoretically possible and has worked for many people, it still can cause random errors, and even BSODs by using mismatched modules.

A RAM module with lower CAS latency will outperform an identical RAM module with a higher CL, this is due to the RAM module with a lower CAS latency fulfilling a data request in fewer clock cycles. But if you were to mix RAM modules with different CAS latencies such as CL16 and CL18, the CL16 module will be forced to run at CL18 which is obviously worse.

When building a PC, it’s best to follow good practises to avoid future headaches such as random crashes and hardware failure. Mixing RAM modules with different specifications especially CAS Latencies can get buggy, so if you want a bug-free experience, it’s highly recommended to use identical RAM modules. But there should be no harm in trying it out, if the experience is bug-free, then consider yourself lucky.


The verdict is mixing and matching RAM is possible nowadays with DDR4 compatibility being more advanced than the previous generations. Back in the day, mixing and matching RAM used to be far more difficult with more incompatibility issues, nowadays the RAM modules are far more flexible being that they’re able to underclock, and undervolt when necessary.

Mixing and matching RAM in a lot of cases will not cause issues, and mixing and matching usually doesn’t occur when you’re building your first PC. Mixing RAM usually happens when you’re upgrading an old build and cannot find the same RAM modules. Mixing RAM modules of different speeds will usually cause the fastest RAM module to clock down to match the slowest module.

Mixing RAM modules with different CAS latencies will cause the RAM module with the lowest CAS latency to raise its latency to match the slower RAM module. This obviously isn’t ideal because it’s inefficient and unpredictable, you’re also not getting the most out of your RAM modules, but this is the price you have to pay when mixing modules.