Today I tried to do it.. there wasn't much space for 2x80mm fans with a bit of improvising managed to attach it onto the Heatsink, but unfortunately I had forgotten that I'm out of thermal paste, due to many times removing applying thermal paste it got depleted. had used up some existing paste on the core and switched on the card.
now even with fans on the Idle temps are 60 degrees. so I'm wondering will applying thermal paste will solve the issue or I will need to change the fans too.