Okay so i'm  going to be replacing my current single fan RTX 2060 (it came with my pc and was made by hp, only has half the memory speed of a normal RTX 2060 and can barely manage 1080p max settings on fortnite and other games. trust me a 1660 super is an upgrade) with a 2-fan 1660 SUPER. My current case is an mATX case and I am pretty sure it can hold the graphics card without any issues, but I am concerned about the airflow after i replace the card. 
 
I currently only have 1 80mm or 90mm fan at the rear of the case as an exhaust (I think its a 90mm but not certain). I don't think that the 90mm alone can keep up as an exhaust with the 1660 SUPER that will be installed. but I don't know if a 120mm fan at the top will give too much exhaust for the case. Obviously, I don't know ANYTHING about proper computer airflow other than rear and top fans are exhaust and front fans ( along with somethings bottom) are intake. So if anyone has any suggestions, please help.
 
My current case belongs to an HP Omen Obelisk 875-0129. The new GPU is the EVGA GTX 1660 SUPER SC 06G-P4-1068-KR. And the 120mm fan i am looking at is the Phanteks PH-F120MP_BBK_PWM. Just for anyone that was the models.


 

Enough airflow?..I doubt it, but you'll have to see what the GPU temperature gets up to..See: Why does my EVGA graphics card run hot? in the EVGA FAQs for more information on GPU temperature.

You should have at least one intake fan, not all exhaust fans..From what I can tell, that PC doesn't have one or even a place for one, like in the front, is that right?..So you might wanna remove and flip over the top fan so it sucks in cooler outside air and blows it in into the case.