I need to increase storage on my gigabyte x570 board with Ryzen 9 3900x cpu. I am use PCIE #1 for video card and the second PCIE slot with the Dual M.2 NVMe. I know that when I bifurcate the second slot, which is a PCIE x8 slot, it causes the first slot, with the video card to become a PCIE x8 slot and the second slot to become a PCIE x4 x4 slot. I installed the card and two m.2 drives, and I ran a speed test and both drives are recognized and ran at advertised speeds! That is great. However, this is the problem…when I transfer data to these drives, specifically from a CFExpress card but as well as from other drives on the computer (m.2 drives are installed in both motherboard slots), the transfer rate starts fast and then will slow down, speed up for the remainder of the data transfer. The typical transfer rate from CFExpress to M.2 drives is around 800 mb/s, such as transfering from memory card to M.2 on the mother board, both on the x570 board and my other build on an x670 board (pro art). I am wondering if this a hardware issue, the expansion card is the problem, the nvme drives are the issue, cfexpress issue, allocation of PCIe lanes or something else? Thanks for your input in advance.
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That’s normal behavior for consumer grade m.2 nvme drives.
Look for reviews that test sustained write performance.
Here is an example of a test.
You can see that all drives start writing very fast for a couple of seconds, then most drop into a slower sustained pattern.
The test reveals that some drives are slower than others or that they have even more write speeds that they alternate between as they write data.
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I did a bit more research on the drives and that seems to be its downside. Kind of a bummer.