In the world of Solid State Drives (SSD) we have new tech most home users haven’t heard of. So, the idea is they can put in an SSD and it will be fast, which is wrong. Only if hardware is matched and properly installed will it be fast.
The video is bit long winded but, it clearly explains what has to be matched and the settings issue.
He did not mention the need for the motherboard to have ample PCIe channels. If one pours all this data into a PCIe bus with only 8 channels nothing is going to be fast. Your new video card likely wants 16 channels but will work with 4… not well. With an SSD wanting 4 channels the motherboard is forced to divide up channels.
If you have anything else using PCIe… things get really crowded.
So, installing an SSD is easy and simple. Getting it to perform at the rated specs is complicated. Not rocket science, just a bunch of details one has to know about.