Gen 4 SSD on Gen 3 slots
Hi, I have a 2018 Mac mini and a Thunderbolt3 NVME SSD enclosure,
I notice that the Gen 4 NVME SSD is getting cheaper and cheaper, I was wondering if one day some Gen 4 NVME SSDs will be cheaper than some of the expensive models of Gen 3 SSD(Samsung 970 Pro for example),
and did anyone test how the speed decrease in Gen3 slot(in my case, a thunderbolt 3 enclosure)
let 5GB/s be the GEN4 SSD read speed, what speed will it be in a GEN3 slot?
will it be the Max speed of gen3 which is about 3.5GB/s, or will it be 2.5GB/s because the bandwidth is half-off?
Did anybody tried and know the real answer?
@yesornofei, Thunderbolt 3 bandwidth throughput is capped at 22Gbps. PCIe 4.0 NVMe drives in a TB3 enclosure work but they don't go faster than this cap.
It's hard to find PCIe 3.0 NVMe drives that can cap the write speed of Thunderbolt NVMe enclosure. Or maybe all my PCIe 3.0 NVMe drives are old...
Here's a test with a Sabrent Rocket NVMe 4.0 2TB using AJA System Test Lite in Big Sur on a Mac mini 2018:
Sabrent Rocket NVMe 4.0 2TB with Trebleet NVMe Thunderbolt enclosure (Alpine Ridge based) read/wite MB/s: 2607/2640
Kind of interesting that write is faster than read in this case.
Here's some tests in Catalina with different PCIe 3.0 NVMe drives: