maps that have lots of surface textures ( yavin ) or lots of white ( rhen var) with lots of snowy white things moving around, use more electricity at the circuit level.
Endor is Texture heavy with all the tree canopy and flying goodies everywhere.
Space map ( besides yavin or hoth ) will use the least, and produce less heat. Electrical cunsumption = heat .

well , testing has many approaches as the test equipment can vary.
the cheapest initial test equipment is reach in and grab the heat sink while its been on for a while.
If you smell meat cooking sorta like bacon in the morning, its hot. ( burning smell, smoke rising, sizzling sounds count also )
The sink should have heat saturation that wont feel really hot. You should be able to hold onto part of it without feeling too hot.
Dust and slow fan is common cause of why stock setups go bad.

Clean the heat sink of dust , BUT DONT BLOW THE FAN WITH AIR PRESSURE EVER and make it spin with the dentists drill sound. I know its fun but it destroys the plastic bearing surface inside the fan and dooms you shortly later.
If you have made the dentists drill sound with your fan already , replace it , lol.
Yes they can turn , but they get slow and they look strong but are 50% capacity sometimes and just suck at half speed.

On the bench testing front, I just open the case and air the thing out good, get all the ribbon cables away from the GPU, etc. It will run cooler and you can see if theres improvement.

But look, if youve Barbequed your graphics card already, we arent going to bring those dead transistors back from the dead... So the next best thing is to have a test card available.

If you have $$ and have access to a heat scope, just scope the cards heatsink and make sure the whole sink is nearly the same temp. If its showing hotspots, theres a cooling problem.

If you have a tri-corder, you can- ...

"The victorious win the battle, then go out to fight ... while the defeated go out to fight, then try to win the battle.   -SunTzu
"The only difference between a capitalist and a communist is that the communist hates competition!" -Circuit