DDR4 and DDR5 are not interchangeable. The memory controller inside the processor supports specific generations, and the motherboard is built around one of them. The slots are keyed differently, so the wrong module will not even seat. Knowing which processors and platforms use which generation answers most compatibility questions before you look at speed or capacity.
How DDR4 and DDR5 differ
| DDR4 | DDR5 | |
|---|---|---|
| Pins (desktop and server DIMM) | 288 | 288, notch in a different place |
| Voltage | 1.2V | 1.1V |
| Power regulation | On the motherboard | On the module (PMIC) |
| Channels per module | One 64-bit channel | Two independent 32-bit subchannels |
| On-die ECC | No | Yes, inside each chip (not a substitute for system ECC) |
| Common speeds | 2133 to 3200 MT/s | 4800 to 6400 MT/s and up |
The moved notch is deliberate: it stops a DDR5 module from going into a DDR4 slot and the reverse. The on-module PMIC and lower voltage mean the two are electrically different too.
Who decides: CPU, chipset or board?
- The processor's memory controller decides which generations are possible. See what a memory controller is.
- The motherboard decides which one you actually get, because its slots are wired for one generation.
- The chipset mostly identifies the platform. It does not handle memory itself, but its name tells you which processors, and so which memory, the board takes.
Intel's LGA1700 platform is the one place where this matters most. 12th, 13th and 14th Gen Core processors support both DDR4 and DDR5, so a Z790 or B760 board can be either. Boards built for DDR4 often have "D4" in the name. Check the board's specification before you buy.
DDR4 or DDR5 by platform
| Platform | Processors | Memory |
|---|---|---|
| Intel LGA1851 (Z890, B860) | Core Ultra 200S | DDR5 only |
| Intel LGA1700 (Z690 to Z790, B660 to B760) | 12th, 13th and 14th Gen Core | DDR4 or DDR5, set by the board |
| Intel LGA1200 and earlier | 11th Gen Core and older | DDR4 (or older) |
| AMD AM5 | Ryzen 7000, 8000, 9000; EPYC 4004 and 4005 | DDR5 only |
| AMD AM4 | Ryzen 1000 to 5000 | DDR4 only |
| AMD TRX50 and WRX90 (sTR5) | Threadripper 7000 and 9000, PRO 7000 WX and 9000 WX | DDR5 ECC RDIMM |
| AMD sTRX4 and sWRX8 | Threadripper 3000, PRO 3000WX and 5000WX | DDR4 |
| Intel W790 (LGA4677) | Xeon W-2400, W-3400, W-2500, W-3500 | DDR5 ECC RDIMM |
| Intel Xeon Scalable 1st to 3rd Gen | Skylake-SP, Cascade Lake, Ice Lake-SP | DDR4 RDIMM or LRDIMM |
| Intel Xeon Scalable 4th and 5th Gen, Xeon 6 | Sapphire Rapids, Emerald Rapids, Xeon 6 | DDR5 RDIMM |
| AMD EPYC 7001, 7002, 7003 (SP3) | Naples, Rome, Milan | DDR4 RDIMM or LRDIMM |
| AMD EPYC 9004, 9005 (SP5); 8004 (SP6) | Genoa, Turin, Siena | DDR5 RDIMM |
For desktop chipsets in more detail, see our motherboard RAM by chipset guide, and for a step-by-step check, how to determine which RAM your chipset supports.
Servers and workstations: DDR4 vs DDR5 for a refresh
On servers the generation follows the processor family. A fleet of EPYC 7003 or 3rd Gen Xeon Scalable servers stays on DDR4 RDIMM for its whole life. Moving to DDR5 means a new platform, not a memory swap. The data center server memory refresh guide covers when that move pays off.
Within each generation the module type matters as much as the generation itself. Servers use registered memory, and some take load-reduced modules for high capacity; see memory types explained.
Shop by generation
NEMIX RAM carries both generations for servers and workstations: DDR4 RDIMM, LRDIMM and DDR5 RDIMM, plus DDR5 UDIMM and desktop memory. Every listing names the systems it fits.
Frequently asked questions
Can I put DDR5 in a DDR4 motherboard?
No. The notch sits in a different place, so a DDR5 module does not fit a DDR4 slot, and the reverse. The memory controller in the CPU also supports only the generation the platform was built for.
Does the chipset or the CPU decide DDR4 or DDR5?
The CPU's memory controller decides which generations are possible, and the board decides which one you get. Intel 12th to 14th Gen processors support both, so each LGA1700 board is built for one or the other.
Which AMD platforms use DDR5?
AM5 desktops (Ryzen 7000, 8000 and 9000), TRX50 and WRX90 workstations (Threadripper 7000 and 9000) and EPYC 9004, 9005, 8004 and 4004 servers. AM4, sTRX4, sWRX8 and EPYC 7001 to 7003 use DDR4.
Which Intel server processors use DDR5?
4th and 5th Gen Xeon Scalable, Xeon 6 and Xeon W-2400, W-3400, W-2500 and W-3500. 1st to 3rd Gen Xeon Scalable use DDR4.
Is DDR5 always faster than DDR4?
It has higher bandwidth at its common speeds, but the right choice is the one your platform takes. See capacity vs speed vs bandwidth for how speed and capacity trade off.
Buying for more than one system
IT teams and integrators that maintain mixed fleets of DDR4 and DDR5 systems can standardize on one kit per model. Request a quote with your models and quantities, or send us your system model and we will confirm the right module before you order.
Steps and rules are summarized from the vendors' published documentation; follow the guide for your exact model.