I recently bought a UGREEN D700 (55316) 40Gbps USB4/TB3 SSD enclosure and put a MIPHI MP300G3 1TB NVMe SSD inside it. I’m using this setup with my Mac Mini M4 over back TB4/3 ports.
Everything was great at first — the speed was super fast. (Read ~3000 MB/s Write ~2700 MB/s)
But after I copied/write around 400GB of data, the write speed dropped a lot. Now I’m getting around 1040 MB/s write, but read is still fast (~2660 MB/s).
I then reformatted the SSD and run the speed test when it is empty, surprisingly the speed becames super fast again!
My Questions: Is this kind of slowdown normal after a large transfers on DRAM-less SSDs? or Could this be firmware or thermal throttling from the Ugreen D700?
I’m suspecting the SLC cache is full and the controller is now writing directly to slower TLC NAND.
Any help, experiences, or tips would be massively appreciated!