4XSSD in RAID 0 VS 1 M.2 SSD
1SSD @ 3500MB/s Read & 2100MB/s Write or 4xSSD's @ SATA-III 6.0Gb/s SSD - 560MB/s Read & 520MB/s Write Witch is faster ?
1) For normal PC workloads RAID 0 has no value.
To keep a single SSD working at full speed you need at least 8 concurrent operations to keep all 8 channels in the SSD working. To keep a 4XSSD array working you'd need at least 4 X 8 = 32 operations at all times.
But windows typically runs at a queue depth of two or less. It would be like a grocery store with 32 open cashiers but only 2 customers with carts... most of the resources of the RAID 0 array would be idle most of the time.
2) Its RANDOM IO you care about, not bulk sequential. You will not get 3.5 GB/sec from an M.2 SSD running 4K random reads. After the first few seconds of operation following trim, 4K random read benchmarks get 10,000 to 50,000 IO per second at a large queue depth. 10,000 4K operations a second is 40 MB/sec, 50,000 4K is 200 MB/sec. Not 3500 MB/sec.
Net, for workloads that matter, judge the speed of the SSD by its sustained 4K R/W random IO mix. Good reviews include this. For example, look at this chart "Random Steady-State" you will see that the lofty 100K IOPS rates earlier in the review drop below 50,000 IOPS for EVERY drive in the review. http://www.tomshardware.com/reviews/samsung-960-evo-nvme-ssd-review,4802-2.html These are the numbers you will actually get,