I've come to realize that GPU temps are dependent on a huge array of factors - it's difficult to optimize all of them while retaining performance.
I have 4x 6950's, they were all running ~85-90C in a case with exceptional airflow. I now have them 'open air' with a ridiculous ventilation system setup to push cold air from an adjacent room directly onto the cards, and I'm getting between 75-85C now.
If your cards are the 'two fan' variety, the only 'intake' is the fans themselves. They will simply expel hot air everywhere, which generally rolls around and gets sucked back into the fans. This is a fatal flaw of these cooler types. Blowing a box fan, etc directly at the cards will make no difference, and may infact increase temperatures, as you're fighting against the exhaust of the cooler fans.
What flags are you using to run your miner? I've found a drastic difference between -f10 and -f30 on my cards with poclbm for example; With -f10, my GPU runs at 99% load and temps raise at least 5C. With -f30, I run at 98% and cooler. I lose about 5mhash/s / card at -f30 (the default).
MSI's website blows and I can't see pics of the card for some reason, so I can't offer more specific suggestions.
For a closed card with turbine fan (reference cooler), intake is at the rear of the card and exhaust is out the back of your case - these are very easy to direct air into.
Dual-fan or non-reference designs with big honkin' heatpipes, etc, are harder as you need to try to prevent the expelled hot air from being recirculated through the card.
If you've re-applied the thermal paste properly (very thin layer spread over the surface of the GPU), and you're getting 83C at full load, you're actually not doing too badly. These cards can usually take the pain, and don't thermal-throttle until 100C+
I'd do more experimenting before spending a bunch of money on aftermarket coolers. Don't get discouraged, it's really not easy to find the right balance.
Great advice there. I've been having similar issues with the non-reference cards and the only solution I've found (when running more than two cards per box) is to run this rather insane delta fan with 240cfm. Luckily my server rack isn't in my living room anymore.
http://www.newegg.com/Product/Product.aspx?Item=N82E16835213001