Superficially - this sounds glorious - but I've only found one* m2 PCIe SSD (SS 970 PRO) that maintains 3000 MB/s after the first 30 - 40 seconds. The worst part is that they drop down to levels that are the equivalent of SSUAX (or PCIe 2.0 x2) transfer speeds (about 690 - 770MB/s).
Test results like this remind me of the VW scandal where the diesel engines were rigged to perform a certain way diagnostically when the engine emissions were being tested and awarded with gold medals from the green olympics committee.
Please test your MP600 again and transfer a 400GB folder from Disk A to Disk B. I suspect you can't for reasons that become obvious as I continue to write..... [you would need another MP600 as the target drive]..
Anyway - I'm genuinely interested to know of a PCIe SSD where the sustained transfer speeds don't fall off a cliff. The invitation to 'recommend' is open to every one here - those Samsung 970 PRO NVMe SSDs are twice the price of all the others on the market - we need a decent alternative!
What temp do you have on the ssd? I used to have a EVO 1TB on a Lycom adapter with passive cooling and got about 50°C. Now I have a Sonnet 4x4 and the temp went down to 30°C. I think the Sonnet is the much better solution IMHO.
From what I understand up to this point - the speed doesn't drop because of thermal throttling. It drops because of the VW trick - the disk flash memory 'cache' fills in 30 secs and then it bottlenecks and falls of a cliff.
I've got my disks in an iocrest syba adapter which provides ample cooling