© SK HYNIX GLOBAL NEWSROOM
DDR5 slots aren’t compatible with DDR4 slots. We might see motherboards that support both DDR4 and DDR5, but you’ll have to choose between one or the other—you won’t be able to install both memory types at the same time. For this reason, I’ve avoided mixed DIMM slot motherboards in the past; I’d rather have four of one type of slot rather than two of each. DDR5 slots will maintain the same pin count as DDR4, 288-pin, but the pin layout will be different, and the slots are keyed with a notch so that you can’t put in the wrong type of memory. Voltages are also different, with DDR5 dropping to a standard 1.1V compared to 1.2V on DDR4.
DDR5 reorganizes the memory chip layout too. DDR5 supports up to 32 memory banks distributed over eight bank groups, compared to 16 banks and four groups on DDR4. The burst length for DDR5 is also doubled to 16, from DDR4’s eight, and DDR5 includes a Same Bank Refresh Function (SBRF) that allows the memory modules to use a different bank to boost throughput.
Besides improved efficiency and throughput, DDR5 boosts the clock speeds. The official JEDEC standard for DDR5 starts at 3200 MT/s, matching the fastest official DDR4 JEDEC speed. Maximum official speeds extend to 6400 MT/s. That means a typical dual-channel desktop or laptop memory configuration will have a maximum bandwidth of 102.4 GB/s— something that should help improve integrated graphics performance. There will inevitably be overclocked DDR5 chips that reach higher speeds. The fastest DDR4 kits can break 5000 MT/s already, and there are already plans for at least DDR5-8400.