I’m pretty sure 1 is for the

I'm pretty sure 1 is for the media (flash) and 2 is the internal controller temp, which is expected to run hot while active (similar to any other internal CPU temp reading).

For the chipset bottleneck thing, consider that most NVMe SSDs don't fully saturate x4, so you see an overall advantage just moving to a RAID-0 of a pair of drives, even if bottlenecked by the controller. Another part of the equation is that random performance still sees a decent boost since most NAND SSDs can't come close to saturating a x4 link when performing more random ops. Another factor is general less loading of the multiple parts dividing the same workload – queue depths will be lower to each drive, and SSD caches are additive across the array, increasing the likelihood that you are writing at full DMI throughput even under heavier loads. I did a review of triple M.2 RAID a while back – shows the advantages off using Latency Percentile, etc.

The slowness observed from an

The slowness observed from an untrimmed external SSD is the result of the additional shuffling of data that must take place in the background. That additional data movement translates to more block erasures for a given amount of host writes (increased write amplification), which means more wear on the flash. Using TRIM is effectively similar to running an SSD with greater amounts of overprovisioning, which is a technique to increase endurance.

For example if you have the ssd on an external usb to sata controller that doesn’t pass the trim command, the performance of the ssd will be much slower if you write the whole disk, then format it and start using it again.

The disk will be empty but since the trim command wouldn’t have passed the cells will be dirty and the performance will be slow (apart from the internal garbage collector of the ssd). But it’s lifespan shouldn’t be affected. The ssd should just be faster if the trim command was supported by the controller.

if that one was an easy answer then here is backup question. ok so people get wound up because intel limits nvme to the dmi bandwidth. if you have 2 970 evos they both basically share a gen 3 x4 lane and one of them can almost max that out alone by itself. but my questiong is what, if any, real world workloads would that actually bottleneck? i mean for video editing you could have 1/3 of that reading from a source drive and a third reading and writing to a a scratch disk and the final third writing to a destination drive. will that actually bottleneck in something like premiere? or anything besides files transfers andor maybe some kind of server app like a database or something crazy?