Well I have about 9 NVME drives in my system and none of them goes above 60C but I guess I do have active cooling for all of them. That is why 74 seemed high to me. Just a question but is your PM981 sitting under a GPU?
It was sitting in an HP portable workstation. It's now replaced by a Corsair MP510 960GB. It sits sandwiched by the ram can and the GPU cooler fan. But I was on desktop, it was using the IGP, and the temps are repeatable. HP sticks a black plastic shield on the drive so that doesn't help, but it's great watching it choke performance while still heating up. I stopped the clone at that excessive temp, because yeah... Then added 80cfm of directed air flow, still hit 80'C but I did have the cover plate on, but the vent holes are right there.
I have found that Samsung SSDs just run hot, unless you give them air flow and coolers. My 840Pro is a warm running thing, and it's in a SATA 300 system. The 850 Pro in my T420s can get warm enough to make the wrist rest warm.
It's why I don't trust Anandtechs benchmarks of SSDs, because there's no way those drives sustain those loads for that amount of time without thermal throttling hard. My 940 Pro in one machine, it doesn't throttle, it stalls, had that replaced under warranty because it got so hot it damaged the NAND.
I have SX8200 Pro and NP, they never got hot like that. The MP510 in that HP under sustained writes will reach the mid to high 60s, and that's in the chipset m.2 or the cpu linked m.2. It also idles a solid 10'C cooler than the PM981.
My SX8200NP sits in air flow from the side panel and ram cooler, and it's got a copper heatsink assembly on it, that's full wrap. The PNP sits in an active cooling adapter with an aluminium heatsink mounted that's the same style as the copper one but twice the fins, so better in active. They both idle under 40'C and loaded won't break 60'C
Side note: I think the Samsung NVME driver may be a bit responsible, as the drives do seem to get warmer with it installed. As compared to just running the stock MS driver with the performance option set, and the PCI-e power saving setting set to off or medium.
Side note: I wish I could find one of the new Optane Memory 4x link drives, to stuff into that HP. I can't find one to even oogle it.
