Q: What is DDR5 memory and when can I use it?

A: DDR5 Memory is a new format

As of Oct 2021, DDR5 memory is starting to ship. It is a new standard for computer Random Access Memory (RAM). Compared to DDR4 memory, DDR5 offers higher speeds and wider bandwidth for a motherboard and CPU to access memory, and it runs at lower voltages.

Q. Can I upgrade my existing machine?

A: No. DDR4 and DDR5 memory cannot be mixed in a system, and they are physically and electronically incompatible, so you cannot upgrade an existing DDR4 motherboard to DDR5.

Original photo courtesy of Kingston

You will need a new CPU and Motherboard

To use DDR5 memory, both your CPU and your motherboard have to support DDR5. Intel’s new Alder Lake CPUs are the first to ship with DDR5 memory controllers built in, and new motherboards with the Z690 chipset are starting to ship as well. Other CPUs and motherboard chipsets will come in the future.

NOT ALL Alder Lake motherboards support DDR5. The Intel Alder Lake CPU is capable of controlling both DDR4 memory and DDR5 memory, so the motherboard will determine whether it takes DDR4 or DDR5. There will be a transition period where motherboard manufacturers offer Alder Lake / DDR4 products until DDR5 is established in the market. Check first before purchasing.

Q: How is DDR5 faster? What about latency?

A: Faster Transfer speeds per clock and more efficient bandwidth

DDR5 memory starts with a DDR speed of 4800 MT/s and so far there are also 5200 MT/s modules on the market. Companies have announced 6400 MT/s and higher modules for future delivery. As we saw with the DDR4 market, the initial entry speeds (DDR4-2133) were surpassed within a year as products came to market and the prices came down and the current mainstream DDR4 speeds are 2666 MT/s up to 3600 MT/s.

The standard CAS Latency of DDR5-4800 modules is CL40, with some performance modules claiming CL38 so far. This is quite a bit higher than DDR4 latencies of 16 to 20. The increased latency mitigates some of the clock speed advantage of DDR5.

DDR5 modules can pack more memory onto a single module (up to 128 GB), so large memory installations will be easier to do.

DDR5 modules implement two memory channels per module instead of one on DDR4, so 4 channels can be implemented with a pair of modules. In addition DDR5 has a larger burst length, so it can transfer data more efficiently than DDR4. Micron quotes a 37% improvement in data bandwidth between DDR4 and DDR5 modules of the same speed, so with the increase in speed to 4800-6400 MT/s we would expect a larger bandwidth improvement in the 80% region depending on the speeds being compared.

DDR5 incorporates on-module Error correction, so it can maintain higher reliability at high speeds. Note that this is not the same as server-class ECC RAM that is implemented from the memory controller, because the on-module correction will not detect errors from outside of the memory chip, such as interference on the motherboard.

Although DDR5 runs at 1.1V (lower than DDR4 1.2V) the addition of onboard voltage regulation (PMIC) and ECC functions means that DDR5 may run hotter than DDR4 memory. Manufacturers are not saying the memory cooling fans will be necessary, but good general PC cooling will be important. The design also means that with additional circuitry on each module, the cost per module will be higher.

Q. How will prices work out?

A: We’ll see. As with any new memory introduction, the first shipments are at a premium price, and inventories will be short. We expect pricing and availability to improve over time with more competition and as more motherboards and machines start shipping with DDR5 chipsets.

Q. Who is selling DDR5 memory?

A: All of the major memory brands will be selling DDR5, both in standard and overclocked versions. As of Oct 2021 Kingston and Crucial have retail pricing in Canada and are on the CanadaRAM website here CanadaRAM DDR5 memory