Same as with any other data transfer: slowest link in the chain sets the maximum speed.
SD card -> USB card reader -> USB controller -> SoC/RAM -> NVMe.
The main difference between 4B and 5 is that NVMe (whether over PCIe or USB3) won't be sharing bandwidth with the card reader as it does on the 4B.
Your SD card might be able to saturate USB2. It's extremely unlikely to be able to saturate USB3 and therefore the NVMe drive. Even less so if you force PCIe gen3.
If your SD cards tops out at 50MBps your 700MBps NVMe drive is going to spend most of its time sitting idle waiting on data from the SD card.
SD card -> USB card reader -> USB controller -> SoC/RAM -> NVMe.
The main difference between 4B and 5 is that NVMe (whether over PCIe or USB3) won't be sharing bandwidth with the card reader as it does on the 4B.
Your SD card might be able to saturate USB2. It's extremely unlikely to be able to saturate USB3 and therefore the NVMe drive. Even less so if you force PCIe gen3.
If your SD cards tops out at 50MBps your 700MBps NVMe drive is going to spend most of its time sitting idle waiting on data from the SD card.
Statistics: Posted by thagrol — Sun Jan 05, 2025 2:28 am
