Troubleshooting guide
How to fix the problem
On some computers, some of the M.2 slots share the same CPU PCIe lanes as the graphics card. Adding an SSD can legitimately switch the GPU from x16 to x8. Whether this is normal is determined by the schematic of the specific board.
Possible solutions
Choose the method that matches your situation. Start with the simplest suitable option and check the result. If the problem is fixed, you do not need to continue with the other methods.
Checking the circuit board
Distinguish between intended line sharing and poor contact.
Steps to follow
- Make a note of the exact board model and the M.2 slot where the second SSD is placed.
- Refer to the manual for the PCIe and M.2 bandwidth table based on the processor installed.
- In the GPU Info app, check the connection width by running its short built-in render test, if provided. At rest, the speed can be reduced for economy.
- Compare the result with the manual. If x8 is provided, it's a design feature, not a Windows bug.
Moving the SSD to another supported slot
Do this only if the alternate slot fits your SSD.
Steps to follow
- Keep a copy of the data and encryption key if the system drive is moved.
- Shut down, disconnect the power, and follow the manual to move the SSD to a slot that doesn't share GPU lines.
- Check the protocol, length and installation of cooling pads for that slot; not all M.2 slots are equal.
- After booting, repeat the GPU connection check and the real application test. If there is no difference, don't go for a higher number just because of the inscription.
If the problem persists
If the number of lines does not match the manual or the connection remains very narrow under GPU load, check the socket, riser and board law. Judge by actual performance: Just saying x8 doesn't prove a bug by itself.
Request a repair