Assuming you're talking about this card?
I mean, the G12 should
fit the 1660TI - but the fan to cool the VRM is going to be totally out of place & mostly wasted. Slight cooling to the VRM, probably - as there's still a little bit of overlap.
You're basically looking at connecting an AIO for the die, then mostly leaving the VRM/memory to open air. Not a great idea, IMO.