CrystalDiskMark is the standard free tool for benchmarking storage drives — SSDs, NVMe drives, and HDDs. A 5-minute benchmark run tells you whether your drive is performing at spec, reveals if there’s a bottleneck, and helps compare drives before purchasing. This guide explains every test and how to interpret the numbers.

Download and Setup

Download from crystalmark.info/en/software/crystaldiskmark — the portable version requires no installation.

Run as Administrator for the most accurate results.

Interface Overview

CrystalDiskMark has four test rows and two columns (Read / Write):

Test	What It Measures
SEQ1M Q8T1	Sequential 1MB blocks, queue depth 8, 1 thread
SEQ1M Q1T1	Sequential 1MB blocks, queue depth 1, 1 thread
RND4K Q32T16	Random 4KB, 32 queue depth, 16 threads
RND4K Q1T1	Random 4KB, single queue, single thread — most real-world

Results show in MB/s.

Reference Numbers by Drive Type

NVMe Gen 5 (PCIe 5.0)

Sequential read: 10,000–14,000 MB/s
Sequential write: 9,000–12,000 MB/s

NVMe Gen 4 (PCIe 4.0)

Sequential read: 4,500–7,500 MB/s
Sequential write: 4,000–6,500 MB/s

NVMe Gen 3 (PCIe 3.0)

Sequential read: 2,000–3,500 MB/s
Sequential write: 1,500–3,000 MB/s

SATA SSD

Sequential read: 500–560 MB/s
Sequential write: 450–530 MB/s

HDD (7200 RPM)

Sequential read: 100–200 MB/s
Random 4K: 0.1–1 MB/s (10–100× slower than SSD)

Most Important Test: RND4K Q1T1

The Random 4K Q1T1 test is the best predictor of real-world desktop performance. This simulates how Windows itself reads and writes — one random small block at a time, with no queue (like opening applications, loading game assets, or writing system files).

Good values:

NVMe: 50–80 MB/s read, 150–200 MB/s write
SATA SSD: 30–50 MB/s read, 100–150 MB/s write

Anything under 20 MB/s random 4K read on an SSD suggests a problem.

Sequential vs. Random Performance

Sequential (large file transfers): matters for video editing, large file copies, backups.

Random (small file access): matters for boot times, app launches, game load times, OS responsiveness.

Marketing specs always show sequential — a drive advertising “7,000 MB/s” is showing SEQ read. Your daily experience is dominated by random 4K numbers.

Running the Benchmark Correctly

Select the drive to test from the dropdown (top right)
Set test size to 1GiB — larger sizes are more accurate but take longer
Keep default 5 loops for consistent averaging
Close browser tabs, background apps, and Discord to reduce interference
Click All to run all tests

For thermal throttle testing on NVMe drives: run the benchmark twice back-to-back. If sequential speeds drop significantly on the second run, your drive is overheating. Consider a heatsink or better case airflow.

CrystalDiskInfo (Companion Tool)

From the same developer, CrystalDiskInfo reads S.M.A.R.T. health data:

Health status: Good / Caution / Bad
Temperature: should be 30–50°C idle
Reallocated Sectors: any number above 0 on an SSD is a warning
Wear Leveling Count: shows remaining SSD lifespan
Power On Hours: total drive runtime

Check CrystalDiskInfo before purchasing a used drive or if you suspect drive issues.

Troubleshooting Low Scores

Symptom	Likely Cause
NVMe showing ~550 MB/s max	Drive plugged into M.2 SATA slot (not NVMe)
Gen 4 NVMe showing Gen 3 speeds	PCIe 4.0 not enabled in BIOS / wrong slot
Sequential fast, random slow	Damaged SSD or nearing TBW (write limit)
All speeds low	Drive thermal throttling — add heatsink
Results vary widely	Drive full (under 10% free = performance loss)

Checking BIOS Configuration

If your NVMe is underperforming:

BIOS → look for PCIe slot settings
Ensure M.2 slot is set to PCIe x4 not SATA
Enable PCIe Gen 4 or PCIe Gen 5 if your CPU and motherboard support it (may require enabling in BIOS)

AMD systems: BIOS → AMD PBS → PCIe Speed → Gen 4 or Auto Intel 13th/14th gen: usually auto-detects — verify in HWiNFO64 sensors

CrystalDiskMark takes under 10 minutes and immediately confirms whether your storage hardware is performing as expected or has a configuration/hardware problem.