Most users only look at synthetic benchmark scores when testing SSDs—numbers like 3500 MB/s read speed look impressive, but they don’t tell the whole story. In reality, performance issues often show up in small file transfers, random reads, or mixed usage scenarios.
Here’s how to benchmark your SSD the right way—and actually make sense of the numbers.
Tools You’ll Need
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CrystalDiskMark – for sequential/random read-write performance
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AS SSD Benchmark – for access time and mixed workload tests
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ATTO Disk Benchmark – for file size-based performance curves
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Real-world testing – stopwatch + file copy methods
Key Metrics That Matter
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Sequential read/write (Q32T1) – shows best-case large file speed
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4K random read/write (Q1T1) – reflects system boot and app launch times
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Access time – crucial for OS responsiveness
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Mixed IO or 70/30 read-write ratios – more realistic workloads
Benchmarking Steps
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Close background apps and pause Windows Defender
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Run CrystalDiskMark using default settings
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Use AS SSD for deeper access time stats
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In ATTO, start with 512B and test up to 64MB file sizes
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Time a real-world task:
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Copy a 10GB folder with mixed file sizes
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Measure how long it takes to copy to and from the SSD
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How to Interpret Results
| Metric | Poor Performance | Good Performance |
|---|---|---|
| Seq Read/Write | <500 MB/s (SATA SSD) | 3000+ MB/s (NVMe SSD) |
| 4K Read/Write | <20 MB/s | 40–60+ MB/s |
| Access Time | >0.5ms | <0.05ms (NVMe) |
If your SSD scores poorly in 4K or mixed workloads, you’re likely to notice lag—even if sequential speeds are high.
Real-World Example
A user upgraded from a SATA SSD to a Gen4 NVMe drive expecting huge gains, but daily performance stayed the same. Why?
4K performance improved only marginally, and thermal throttling kicked in during sustained loads. Only after proper thermal pads were installed did the system feel faster.
Synthetic scores are just part of the story. Test like a pro, and you’ll know exactly where your SSD stands.