well something's not right. that idle temps is too high.
load temp seems a bit high, but within limits.
What is your room temp like?
I see that the side of the case has 4 fan housings, can you put fans in the bottom two placements?
As a test. remove the side of your case, place a desk fan about 10-15 cm away from the case, turn it too a medium speed, then check your gpu temps. If they decrease (which hopefully they will) then you have an airflow problem inside the case (which is what I suspect - without side fans, those gpus are getting starved of air when the gpu fans are at low speed)
Also TIM is Thermal Interface Compound. It is a thick liquid that you spread on top of your CPU and GPU before mounting the heatsink. It fills in all the mircoscopic holes to ensure proper transfer of heat from the GPU/CPU to the heatsink.
Too much, too little or incorrect application can mean that heat won't transfer properly, leading to overheating problems.
This wikipedia article is a good read, explains all about computer cooling, including thermal compounds.