The program needs to create a test file on the selected drive. If it fails:
Run as Administrator: Right‑click CrystalDiskMark → Run as administrator. UAC: choose Yes.
Check that the drive has enough free space for the test size (e.g. 1 GiB free for 1 GiB test).
Ensure the drive is not read‑only or locked by another app.
Temporarily disable or exclude the folder from antivirus/real‑time protection; some AVs block disk benchmark tools.
Network drive not in the list
When running as Administrator, network drives are hidden. Run without admin rights (UAC dialog → No) so the network drive appears in the drive list. See FAQ.
Results much lower than expected (e.g. NVMe SSD slow)
Try the following:
Use the NVMe SSD profile (Profile → NVMe SSD) so queue depth and threads are appropriate.
Close other programs that use the disk (browsers, backup, Windows Update, game launchers).
Check that the NVMe drive is in a proper M.2/PCIe slot and not limited by SATA or shared lanes.
Update the storage/NVMe driver and chipset drivers from the PC or motherboard vendor.
Ensure the drive is not thermal throttling; allow it to cool and run the test again.
Program won't start or crashes on startup
Possible fixes:
Install the latest Visual C++ Redistributable (e.g. from Microsoft). CrystalDiskMark may depend on it.
Download again from a trusted source; avoid third‑party download sites.
If using ZIP, extract to a folder with a short path (e.g. C:\CDM) and avoid paths with special characters.
On Windows 11, ensure Windows Update and graphics drivers are up to date (older versions had some compatibility fixes in CDM 8.0.3/8.0.4).
Antivirus blocks or deletes CrystalDiskMark
Some security products flag disk benchmark tools because they do low‑level disk access. Official builds are digitally signed. Add an exclusion for the CrystalDiskMark folder or executable, or temporarily disable real‑time scanning for the test. Use a trusted source to avoid tampered builds.
Save as Image or Copy doesn't work
If "Save as Image" or "Copy" fails or produces blank output, try running the program as Administrator once. On Windows 11, earlier versions had fixes for Save as Image and High Contrast (see CDM 8.0.4). Make sure you're on the latest 9.0.2 (or at least 8.0.4+) and that display scaling is set to a supported value.
USB drive or SD card: very slow or test fails
Use a small test size (e.g. 16 MiB or 32 MiB). Large tests (1 GiB+) can timeout or fail on slow media. Also ensure the USB port is USB 3.x if the device supports it, and that the drive is not corrupted (check with chkdsk or CrystalDiskInfo).
For support, check the program’s help or documentation.