well my pc case is old core 2 duo SFF lenovo thinkcentre A/M57 : https://www.newegg.com/lenovo-m57-business-desktops-workstations/p/N82E16883798350
it doesnt have good airflow considering there is only oddly positioned 1x 80mm cpu fan and psu fan.
since GT 710 has overheating problem, i am using GT 730 nowadays (https://www.asus.com/motherboards-components/graphics-cards/asus/gt730-sl-2gd5-brk/). it has double-slot sized thicker heatsink but still passive cooling. i am getting 28-35C idle temps and max 70C on gaming with GT730.
so you say overheating problem with GT 710 is normal while gaming? but i am playing old XP games only. i know these cards are not gamer cards but games i play shouldnt be so demanding.
another example, before this core2duo case, i was using GT 710 on my other SFF lenovo thinkcentre M92p model (3rd gen i5). it is slightly bigger, more space and airflow with extra 80mm exhaust fan. i was getting 25-30C idle temps, and around 60-65C on load. still i cant get why there are too much heat difference between 2 cases.
now my only concern is heat except driver issue with my GT 710.
only reason i insist using GT 710 is the core2duo sff pc i got recently to make it XP gaming machine for old games. I know standard ATX case would be much better for airlow and card selection but I like small form factor more.