HMB is a feature that lets a solid-state drive borrow a small portion of your computer's main memory (RAM) to store frequently accessed data and speed up operations. Instead of keeping a large memory chip on the drive itself, the SSD delegates this job to your system RAM.
When you use HMB, the drive reserves perhaps 64 MB to 256 MB of your RAM as a buffer. This borrowed space acts like a fast waiting area for data the drive expects you to need soon. The result is quicker read and write speeds, especially for everyday tasks like opening files or launching applications.
For example, a budget NVMe drive without dedicated DRAM might slow down during sustained file transfers. With HMB enabled, it borrows RAM from your system and maintains much faster speeds throughout the operation.
- Compatibility: Your motherboard firmware and operating system must support HMB. Most modern systems running Windows 10 or later, macOS, or Linux do.
- RAM trade-off: The borrowed memory is unavailable to other applications, though the amount is usually small enough that you won't notice in day-to-day use.
- NVMe only: HMB is specific to NVMe SSDs; SATA drives don't use it.
When comparing budget SSDs, check whether the drive uses HMB or has onboard DRAM. Both can deliver good performance, but understanding which your drive uses helps explain speed differences in reviews. If your system supports HMB and you're buying a DRAMless drive, ensure this feature is enabled in your BIOS for the best real-world performance.