Hi
@DominicB06
Max ref. temp for the 1660 is approx. 95c. You of course don't want it anywhere near that hot. A quick search brought up similar issues as yours as it appears the cooler on some 1660's did not employ the best overall design.
* Have you updated the drivers recently? Close out all un-needed background apps and try rolling back to an earlier driver ver. A side effect is that some drivers can raise temps as they make other tweaks to how the card runs.. (New game support & whatnot)
* Do you have a fan control program like
MSI Afterburner or
Precision X1 installed? If not, I'd advise it. I'm partial to EVGA's Precision X1, which works with every GPU, not just those from EVGA.
* How old is the 1660? Did you buy it new? Used? If it's not under warranty, I'd suggest you consider replacing the thermal paste. Possibly it was applied on a Friday afternoon just before quitting time and so it might not have been applied correctly &/or has started to dry out. (probably not, but still worth a check)
Of course the inside of your case is clean & clear of dust? The overall ambient temps of the room the PC is in is not overly warm to begin with? The best cooler will suck if it's only moving hot air.
A little more info please. While you're at it, whats the rest of your system look like, namely your PSU.