I have bought that SSD, and I am disappointed.
It turns out that Samsung 870 EVO does not work correctly with ATI/AMD SB7x0/SB8x0/SB9x0 SATA controllers (AHCI mode). I installed this SSD in my ASUS K42DR laptop (it is connected directly to the motherboard, without any cables or adapters). I am aware that my laptop supports only SATA II standard, but the SSD is not even close to SATA II speed limits. Unfortunately, Samsung 870 EVO SSD shows very poor performance because of constant HDMA CRC errors (the value in SMART stats raised above 1500 in 3 days of device's operation). The problem is present on both Windows and Linux OS. I dug into the problem, and found out that the root cause may be connected with SATA NCQ malfunction (there are numerous queued READ/WRITE errors). There are lots of information on the Internet about the same issue with Samsung 860 EVO.
IMHO, the worst part is that there is no warning about that compatibility issue nor on Samsung site nor on device's package itself. Depending on the country, that issue may or may not be covered by Samsung limited warranty. Providing the issue has not been fixed on Samsung 860 EVO, there is no hope that they will fix it on 870 EVO either.
There are reports on the Internet about the same incompatibility issues with certain Intel chipsets, but I can't prove or disapprove these cases.