SATA, PCIe and NVMe compared

In short: SATA, PCIe and NVMe are not competing storage devices but layers: SATA is an older interface with a cable, PCIe is the motherboard’s fast data bus, and NVMe is the modern protocol that runs over PCIe and was designed specifically for flash storage.

In more detail: You must distinguish physical connection (connector, bus), protocol (language) and form factor (case). An M.2 SSD can, for example, have SATA or NVMe technology even though it looks the same.

In Depth

	SATA (III)	PCIe	NVMe
Kind	Interface + protocol (AHCI)	High-speed bus	Protocol (for flash)
Max. speed	600 MB/s (~550 real)	4.0 x4: ~7.9 GB/s, 5.0 x4: ~15.8 GB/s	uses PCIe bandwidth fully
Lanes/queues	1 channel, 1 queue with 32 commands	per lane a serial pair, x1/x4/x8/x16	64,000 queues with 64,000 commands each
Latency	higher	low	very low
Typical devices	2.5” SSD, HDD, optical drives	Graphics cards, SSDs, network cards	M.2/U.2 SSDs
Connection	SATA data cable + power	Slot (x1…x16), M.2	M.2 slot (M-key), PCIe add-in card

Relationships:

• SATA: Was designed for spinning hard drives (AHCI protocol). With SSDs the interface becomes the bottleneck at ~550 MB/s.
• PCIe: General bus, in generations (3.0, 4.0, 5.0, 6.0), each doubling the rate. Lanes are bundled: x4 = four lanes.
• NVMe (Non-Volatile Memory Express): Protocol that regulates access to flash far more directly and in parallel than AHCI. Runs over PCIe, so NVMe SSDs reach 3 – 14 GB/s.
• M.2: Only the slot/form factor (small board). Can carry SATA or PCIe/NVMe, recognizable by notches (B-key, M-key). Check before buying what the motherboard supports.

Decision aid:

• Old system, notebook without M.2 NVMe: SATA SSD, still a big leap over HDD.
• New system: NVMe PCIe 4.0 SSD as system drive.
• Large data/archives: HDD on SATA.
• In daily use you feel less between SATA SSD and NVMe than between HDD and SSD. With large files or games NVMe drives are faster.

Cooling: Fast NVMe drives get hot (throttling), heat sinks help.

See also: SATA, PCIe, NVMe