DDR4 vs DDR5: Speed, Latency, Compatibility and Which to Buy

DDR5 is the newer memory standard: it transfers data at 4,800 to 8,800 MT/s against DDR4's maximum of 3,200 MT/s, runs at 1.1 V instead of 1.2 V, and splits each module into two independent channels. The two are not interchangeable, so your motherboard decides which one you can use, and real-world latency is about the same.

DDR4 vs DDR5 at a glance

The figures below are from Micron's DDR4/DDR5 comparison unless noted.

"MT/s" is megatransfers per second. Shops often write the same number as MHz (DDR5-5600 sold as "5600 MHz"), but the actual clock is half that figure because DDR memory transfers twice per clock cycle.

Is DDR5 faster? Bandwidth vs latency

"Faster" means two different things for memory, and DDR5 only wins clearly on one of them.

Bandwidth: DDR5 wins

Peak bandwidth is transfer rate times bus width. A module's data bus is 64 bits (8 bytes) wide on both generations; DDR5 just splits it into two 32-bit halves. So:

These are theoretical ceilings; measured throughput is lower on both. The two subchannels and the doubled number of bank groups also let a DDR5 module serve more requests in parallel, which Micron credits for better performance under multitasking. Work that streams lots of data benefits most: integrated graphics (which use system RAM as video memory), video encoding, large compiles, simulations and running AI models on the CPU.

Latency: roughly a tie

CAS latency (CL) is counted in clock cycles, and DDR5's cycles are shorter, so the raw CL numbers aren't comparable. Convert them to nanoseconds:

latency (ns) = CL × 2000 ÷ transfer rate (MT/s)

A DDR5 kit with CL30 sounds much slower than a DDR4 kit with CL16, but both reach the first word of data in 10 ns. Entry-level DDR5 with high CL can actually be slower per access than good DDR4. Programs that make many small, scattered memory accesses (some games among them) care more about this number than about bandwidth. Compare kits in nanoseconds, not CL.

Are DDR4 and DDR5 compatible?

No. Micron's FAQ is direct: "DDR5 memory and DDR4 motherboards are physically and electrically incompatible." The page adds that DDR5 RAM only fits DDR5 motherboards and DDR4 RAM only fits DDR4 motherboards. A module that doesn't slide in easily is the wrong type; don't force it.

The processor is less of a constraint than the board. Some CPUs have memory controllers for both: Intel lists the Core i7-13700H, for example, as supporting "Up to DDR5 5200 MT/s" and "Up to DDR4 3200 MT/s". But each motherboard or laptop is built for one type. To know what you need:

• Check your board's or laptop's specification page for the memory type.
• Or read it from the system: how to check RAM speed shows a PowerShell property that reports the DDR generation of installed modules.

Note also that the CPU's specification sets a maximum speed. The i7-13700H above tops out at 5,200 MT/s for DDR5, so faster modules in that laptop run at 5,200.

Advertised speeds and XMP

Desktop memory is often sold at a speed above the standard, for example DDR4-3600 or DDR5-6000. Those speeds are factory-tested overclocking profiles. Intel says XMP modules "will first boot with the default JEDEC settings" and only run at the profile's speed after you enable XMP in the BIOS. On some boards the setting has a different name, such as EXPO or "memory profile". If you buy fast memory, check after building that the profile is on, otherwise you are paying for speed you don't get.

Power and reliability differences

DDR5 lowers the core voltage from 1.2 V to 1.1 V, and moves voltage regulation onto the module with a power management IC (PMIC). Samsung describes the on-module PMIC as enabling "more efficient power regulation and stable power delivery". The practical effect on a desktop power bill is small; it matters more for servers with many modules and for laptops.

DDR5 chips also include on-die ECC, which corrects single-bit errors inside the chip. It's not the same as ECC memory: errors on the path between module and CPU aren't covered, and full ECC still requires ECC modules plus a supporting CPU and board.

Which should you buy?

Capacity usually matters more than generation: a system that runs out of memory and starts swapping to disk slows down far more than the gap between DDR4 and DDR5. Get the amount right first with how much RAM do I need, then pick the fastest kit your CPU's specification supports.

Frequently asked questions

Can I put DDR5 RAM in a DDR4 motherboard?

No. Micron states that DDR5 memory and DDR4 motherboards are physically and electrically incompatible: DDR5 only fits DDR5 slots and DDR4 only fits DDR4 slots. Some CPUs support both types, but each motherboard is built for one of them.

Is DDR5 faster than DDR4 for gaming?

It has much more bandwidth, but real latency in nanoseconds is similar, and many games depend more on the GPU. The gain varies by game and resolution, so look at benchmarks for your specific CPU and games rather than expecting a fixed percentage.

Does DDR5 on-die ECC mean I have ECC memory?

No. DDR5's on-die ECC corrects single-bit errors inside each memory chip before data leaves it. Full ECC memory, as used in servers, adds extra bits per channel so the memory controller can detect and correct errors on the way to the CPU. That requires ECC modules and a CPU and board that support them.

Should I upgrade from DDR4 to DDR5?

Only as part of a platform upgrade. Switching memory type means a new motherboard, and often a new CPU. If your current DDR4 system has enough memory, adding or replacing DDR4 modules is far cheaper than moving to DDR5 for the memory alone.

Sources

• Micron: DDR5 SDRAM (DDR4 vs DDR5 comparison and FAQ)
• Samsung Semiconductor: DDR5
• Intel: Core i7-13700H processor specifications (memory types)
• Intel: Extreme Memory Profile (XMP)