M.2 Adapter x4 PCIe 3.0 NVMe Speeds ??

Have a question about these adapters and the Corsair 510 i am using. I am using a ASUS prime b-350 plus motherboard and have a Samsung 960 NVMe HD in the m.2 on board socket and runs well and fast as it should, but the new corsair 510 i have using a Startech adapter is running well short of the speeds it can reach like 1500 max read and write which is like half what it can do.

Is there a speed limit with these adapter or is it due to the motherboard/adapter/driver you are using ?. This is my first time using one so bit unclear on how they work and the like.

Also the driver that is being used is way old from 2006, any newer driver out there at all.

Any feed back would be great and thanks in advance.

I'm inclined to think that it's the adapter or the configuration. It sounds like you are running in x2 mode.

First, StarTech has several NVME adapters. Which one do you have?

Second, make sure that the PCI Express slot that you have it in supports full x4 PCIe. You may need to enable this in the BIOS - many motherboards default secondary (non Primary GPU) PCIExpress connectors to x2, even though electrically they are x16. You may need to flip this.