googled for PM961 warranty TBW (after a few tries)
Correct...that is just the warranty. A LOT of drives can exceed that number 10 fold.
In actual use, you will never ever get close to that.
From several years ago:
https://www.anandtech.com/show/7173...w-120gb-250gb-500gb-750gb-1tb-models-tested/3
Six weeks have passed since our last SSD endurance update. When we last visited our heroes, they had just crossed the half-petabyte threshold—no small feat for a collection of consumer-grade...
techreport.com
"By far the most telling takeaway thus far is the fact that all the drives have endured 600TB of writes without dying. That’s an awful lot of data—well over 300GB per day for five years—and far more than typical PC users are ever likely to write to their drives. "
"At this rate, even the 840 Series may reach a petabyte of writes before burning out. The others are on track to cross that threshold easily, and I expect we’ll be waiting a long time for their eventual demise. "
In terms of write cycles, your 1TB will long outlast this PC, and the next two.