SSD DRAM Cache: Why It Matters for Gaming

What is an SSD DRAM cache?

This article explains a storage feature that does not get enough attention on a spec sheet: the DRAM cache. SSDs store data in NAND flash memory, but the controller on the drive needs a list that maps the logical addresses used by the operating system to the physical locations on the NAND chips. That list is called the flash translation layer, and keeping it in fast memory matters for steady performance.

Some drives put a small DRAM chip on the circuit board to hold that list. The chip is commonly described as a DRAM cache, an onboard DRAM buffer, or simply SSD DRAM. It lets the controller update the address table without extra reads from NAND. To understand the basics of drive storage, start with what is an SSD and NVMe SSD explained.

DRAM cache versus Host Memory Buffer

Not every SSD includes its own DRAM. Many newer NVMe drives are DRAMless to keep the circuit simpler. The NVMe specification includes a Host Memory Buffer, or HMB, that lets a drive request a small portion of the system's RAM. The controller then places its address table in that borrowed memory instead of on an onboard chip.

HMB works over PCIe and is available for NVMe drives. SATA drives do not use HMB, so their controllers either include DRAM or manage without it. For a closer look at the two interfaces, see SATA vs NVMe SSD.

What sustained write performance means

Sustained write performance is the behavior that separates drives more clearly than the first burst of speed. When you install a long game, copy a large folder, or move a library from one drive to another, the drive writes continuously for a while. If the address table stays in DRAM or HMB, the controller can update it quickly and keep a steady pace.

A DRAMless drive without HMB must save the table to NAND from time to time, which can cause the write rate to drop or become uneven. Read operations, which make up most game activity, are less sensitive to this. The operating system also takes space on the drive; Windows 11 lists at least 64GB as the minimum storage device, and a library of titles extends far beyond that, so sustained writes matter during the initial setup of a library.

The comparison DRAM cache vs DRAMless SSD explains the two designs in more detail.

Does a gaming PC need a DRAM cache?

For gaming, the day-to-day workload is mostly reads. The drive loads model files, textures, audio, and saved worlds into system memory. Those reads come from NAND, and the address table in DRAM or HMB helps the controller find the right blocks. A well-designed DRAMless NVMe drive with HMB is generally enough for a game library, and many prebuilt gaming PCs ship with one.

Onboard DRAM is a preference when you want the drive to handle sustained writes without relying on system memory. If you play at a higher resolution and keep several large single-player games installed, a drive with onboard DRAM is a reasonable choice. The guide how to choose an SSD with DRAM cache goes into the feature in more depth.

How to read the storage section of a spec sheet

When you compare storage specs, look for lines that say DRAM cache, onboard DRAM, Host Memory Buffer, or DRAMless. A listing that only says NVMe SSD or PCIe 4.0 does not tell you whether HMB is supported. Some makers include HMB support in the controller description, so you may need to open the product page.

For a prebuilt gaming PC, the storage drive is already inside the machine, so read the full spec sheet before ordering. The related article what to check in a gaming PC for storage interface covers the interface side of the same decision.

What to pick for your kind of play

A standard gaming build works well with a current NVMe SSD, either one with HMB or one with onboard DRAM. If you play at a higher resolution and keep several large games installed, a drive with onboard DRAM is worth the attention. If you also edit video or move large project files, onboard DRAM helps keep sustained writes steady. For the fastest interface on current platforms, PCIe 5.0 SSDs are available, and a platform that supports them can use their full bandwidth; NVIDIA lists PCI Express Gen 5 on the GeForce RTX 50 Series as part of that current generation.

See the SSD buying guide and the PCIe 5.0 SSD guide for comparisons based on stated specs. If you are buying a prebuilt, check the drive before you order in the prebuilt gaming PC guide.

What to pick for your play

Questions

What is a DRAM cache on an SSD?

It is a small memory chip on the drive that holds the address table, known as the flash translation layer, and a write buffer. It helps the controller manage NAND without extra reads.

What is the Host Memory Buffer (HMB)?

HMB is an NVMe feature that lets a DRAMless drive use a small portion of the system's RAM for the same address table. It is available over PCIe for NVMe drives, not for SATA drives.

Is a DRAMless SSD bad for gaming?

No, for game storage. Games mostly read data, and a good DRAMless NVMe drive with HMB can keep the address table in system RAM. A drive without HMB or DRAM may be less suited for long sustained writes.

Does HMB use the PC's RAM?

Yes, a small area of system RAM is reserved while the drive is connected and the feature is enabled. The amount is set by the drive and is small compared with system memory.

How can you tell if an SSD has DRAM cache?

Check the maker's product page or spec sheet for "DRAM cache", "onboard DRAM", "Host Memory Buffer", or "DRAMless". If only the interface is listed, the drive may not have a clear cache note.