I have a Zotac gtx670, its just at stock clock speeds and stock everything. When i play BF3 or Borderlands 2 my 670 gets up to 80 degrees celsius and the fan starts going really fast and loud. I have cleaned it out and gotten rid of any dust in there and it still got really hot. My case is a Corsair Graphite 600t special edition with just the default fans, 200mm on front and top and a 120 on the back, i have also tried turning these up to full speed and it didn't work.
or i could put on the other side panel that my case came with and add 4 120mm side fans blowing onto the gpu. This would cost me $50.
I would prefer the second option because it is cheaper and in the future i plan on adding another 670. If i went for the first option and added another 670 i would have to buy another aftermarket cooler for the second card.
Would the four side fans drop my temps a significant enough amount? or would i have to buy the aftermarket cooler to see any difference?
Side fans intaking cold air help a ton. I don't even think you would need 4. Mine just has one 120mm above the graphics card and it helps a lot. I would definitely try that first because 120mm fans are pretty inexpensive and doesn't involve potentially voiding your warranty.