What about my question
How much space do you have between your hard drives? Would it be possible to separate them some if they are packed in there against each other?
If they are close to each other there may not be decent airflow and this would cause/contribute to heating issues.
Did you clean out your Power supply? if it's hot due to dust buildup, the fan for the Power supply usually blows into your case.
Looks like you may need to get/upgrade a fan or 2. Take a look at your computer location. Any direct sunlight? Any way to get it into a cooler environment? (even a small change could help.)
I'm thinking you may want to invest in some fans... take a good look at your case, see if you have space for a larger fan (to replace a fan you already have). Also check to see if you have a place to add a fan.
Wait... check to see if you can bump up fan speed in your BIOS... (may not need a new fan, just faster old fans)