AS SSD Benchmark vs CrystalDiskInfo: Benchmark vs Health Monitor
AS SSD Benchmark and CrystalDiskInfo are confused constantly, partly because their names sit next to each other in download lists and partly because both are free Windows staples. But they do opposite kinds of work. AS SSD Benchmark actively stresses a drive and times it. CrystalDiskInfo passively reads the drive’s own self-monitoring data and reports its condition. A fast drive can be dying; a healthy drive can be slow. This page explains the division of labour — what AS SSD does not tell you, what CrystalDiskInfo does not tell you, and how to use the two together. AS SSD is available on our download page.
What AS SSD Benchmark tells you — and what it never will
AS SSD measures performance: sequential throughput, 4K and 4K-64Thrd random throughput, access time, copy-test times for ISO, Program and Game file sets, and throughput across data compressibility. It summarises the synthetic tests into a total score, and its header shows the drive model, firmware, controller driver and alignment status. All of that describes how the drive performed during a few minutes of testing, on that day, in that system.
Here is the list it does not cover, in full: no SMART attributes, no health percentage, no temperature, no power-on hours, no total bytes written, no remaining-life estimate, no error counts, no firmware update, no secure erase. AS SSD has no health features at all — it is a benchmark, not a monitor. A drive one week from failure can post a perfectly respectable score, because failing drives often perform normally until they do not. If your question contains the words health, lifespan, temperature, wear or safe, AS SSD is the wrong tool no matter how good its score looks. To understand the scores themselves once you have them, read how to read AS SSD scores.
What CrystalDiskInfo tells you — and what it never will
CrystalDiskInfo, from the same Crystal Dew World project family as CrystalDiskMark, reads the SMART (Self-Monitoring, Analysis and Reporting Technology) data that drives maintain about themselves. It presents a plain health status, the drive’s temperature, and the underlying attributes — items such as wear indicators, error counts, power-on time and the volume of data written, depending on what the drive exposes. It can sit in the background and warn you when a value crosses a threshold. That is exactly the early-warning system a benchmark cannot provide: it watches the drive’s own account of its condition, continuously, without running a single speed test.
Its blind spot is the mirror image of AS SSD’s: CrystalDiskInfo cannot tell you how fast anything is. A drive can report perfect health while delivering miserable performance because it is nearly full, connected to a slow port, running in the wrong controller mode or simply an old, slow model in flawless condition. Health data also depends on the drive reporting honestly and completely; treat a clean SMART report as strong reassurance, not a guarantee, and keep backups regardless. (For deeper diagnostic work such as full surface scans, a suite like HD Tune Pro goes further — see AS SSD Benchmark vs HD Tune.)
Side-by-side comparison
| Dimension | AS SSD Benchmark | CrystalDiskInfo |
|---|---|---|
| What it measures | Active performance tests: Seq, 4K, 4K-64Thrd, access time, Copy and Compression | No measurement — reads SMART health data: status, temperature, wear and error attributes |
| Score / result form | MB/s or IOPS per test plus a weighted Total score | Health status verdict and an attribute table with current and threshold values |
| Platform | Windows only; portable | Windows |
| Licence and price | Freeware by Alexej Schepeljanski; free | Free, from Crystal Dew World (Noriyuki Miyazaki’s project family) |
| Maintenance status | Final version 2.0.7316.34247, January 2020 | Part of the actively maintained CrystalDisk family (CrystalDiskMark 9.0.3, May 2026) |
| Best for | Answering “how fast is it?” and comparing drives by score | Answering “is it okay?” — ongoing health, temperature and wear watch |
Using them together: the two-question routine
Every drive check should ask both questions, in this order. First, health: open CrystalDiskInfo and read the status and temperature. If the status is anything other than good, stop testing, back up or clone the drive, and treat performance as irrelevant until your data is safe. Second, performance: run AS SSD Benchmark and compare the result with the drive’s class and with your own earlier results. Low scores with good health point to configuration — alignment and controller mode are shown in AS SSD’s own window — or to a drive that is full or simply slow by design. Good scores with declining health point to replacement planning, not celebration. Records matter: save the AS SSD screenshot and note the health figures on the same date, and a trend over months becomes visible, which is worth more than any single reading.
Two scenarios that show why both matter
Consider a drive that benchmarks beautifully — strong sequential figures, a healthy total score — while its SMART data shows a rising error count and a health status that has slipped from good to caution. Trust the health data: back up immediately, because the benchmark has only proved the drive was fast on the day it may be preparing to fail. Now consider the opposite: SMART reports perfect health, yet AS SSD scores are half what the drive’s class should produce, and its window shows a partition-alignment warning. Trust the benchmark: the drive is not dying, it is misconfigured, and fixing the configuration is free. Neither tool alone could have reached the right conclusion in both cases, and applying the wrong tool’s verdict — celebrating the first drive’s speed or replacing the second drive outright — wastes either data or money. That is the whole argument of this page in miniature: speed and health are separate facts about a drive, each tool reports one of them faithfully, and a complete check always asks for both.
Verdict by scenario
“How fast is my SSD?” AS SSD Benchmark. “Is my SSD healthy, hot or worn?” CrystalDiskInfo — AS SSD cannot answer at all. “My system feels wrong and I don’t know why”: CrystalDiskInfo first for safety, AS SSD second for speed, in that order. The pair costs nothing, takes minutes, and together they cover the two questions every drive owner actually has. Neither replaces the other, and using only one leaves exactly half the picture blank.
Get AS SSD from the download page, and see where both tools sit in the full landscape in our best SSD benchmark tools overview.