Why NVMe SSD Not Running at Full Speed

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Sherly· Answered on Mar 29, 2025

Regarding your question, I first thought of two answers. The first one is the bios PCIe setting. You need to check if yours is normal. The second is to try again with reliable speed measurement software. Next, I will describe in detail how to operate.

Stage 1. Check BIOS PCIe

Step 1. Restart the computer and enter the BIOS by pressing the appropriate key during startup. This key can vary by computer make, and model but is usually F1, F2, F10, Delete, or Esc.

Step 2. Navigate to the "Advanced" or "Advanced Setup" tab in the BIOS.

Step 3. Look for and choose the "PCIe Configuration" or "PCI Express Configuration" options, which may be on the "Advanced" tab. 

Step 4. In the PCIe configuration menu, switch M.2 mode from x2 to x4.

Step 5. After making the desired changes, save and exit the BIOS by selecting "Save and Exit" or "Exit and Save Changes" from the menu. By the way, changing the PCIe settings in the BIOS can have a significant impact on system performance and stability. Use caution when adjusting these settings, and make changes gradually while monitoring system behavior for any adverse effects.

Now, you can turn to Stage 2 and use a reliable SSD benchmark to test the speed again. It is also possible that your former test result is inaccurate, so you can use EaseUS Partition Master to try again. 

Stage 2. Test SSD Speed Again

This tool is easy to use and can display the random write or read speed and the peak speed your SSD can reach. Here is how:

Step 1. Launch EaseUS Partition Master and activate the "Disk Mark" feature in the "Discovery" tab.

Step 2. Then, choose the target SSD, test data, and block size. Finally, click "Start" to test.

In this way, you can get an accurate result. If the read/write speed of your SSD is still slow, you can try to 4K Align your SSD to optimize it. Click the link below to learn how: