There could be several reasons why your external M.2 SSD is slowing down to 40 Mbps write speed. It's unlikely that the SSD itself is faulty, as M.2 SSDs are generally reliable. However, there are a few potential causes, such as a loose connection, a worn-out USB port, or a driver issue on your computer. You can try checking the connection, updating your drivers, or using a different USB port to see if that resolves the issue.
External M.2 SSDs can experience slow write speeds due to factors such as limited bandwidth, compatibility issues with the host system, or the use of outdated firmware. Additionally, the presence of a controller or bridge chip may also contribute to reduced write speeds.
Qiling Disk Master Free is a software that checks and manages SSD write/read speeds, with a feature called "4K Alignment" that optimizes storage configuration for improved performance.
You can follow the steps here to check the SSD speed first:
Step 1. Launch Qiling Disk Master and go to the Discovery tab.
Step 2. To run the DiskMark feature, select it and then choose the target drive, test data, and block size.
Step 3. To run a disk test, click "Start". This will display the Sequential or Random read/write speed, I/O, and Delay data.
4K Alignment is a process that optimizes the performance of solid-state drives (SSDs) by aligning the storage blocks to a 4K boundary, which is a 4096-byte boundary. This process can improve the read and write speed of the SSD by reducing the number of fragments and increasing the efficiency of the storage system.
Step 1. Go back to Qiling Disk Master and go to the Toolkit tab.
Step 2. Select the "4K Alignment" feature and then choose your SSD.
Step 3. Click "Start" and wait patiently.
Related Article: To fix slow SSD write speed on Windows 10/11, try running the built-in Disk Cleanup tool, disabling unnecessary startup programs, and checking for disk errors. You can also enable the "Quick Removal" policy for USB devices, disable Windows Search, and check for malware.