what sort of cooling pad did you get?
something like this has a very large silent fan (i've used one), that is underneath and powered by a USB port:http://www.notebookcheck.net/Review-Lia ... 350.0.html
Based on the steps you've taken however, in my experience with overheating gfx on laptops you're just out of luck if you already have a fan-based cooling solution like I just mentioned. If not, that may be your only realistic option.
The fan on the lian li nc09 is silent and depending on how your laptop vents and chassis are setup, you may feel the slightest of slight cool breeze coming up from beneath the keyboard (especially with a bit of the underside of the case removed like you mentioned), but it does not move enough air to actually chill your fingers.
And yes, at $65 it is expensive, but it does work to drop temps significantly in higher-end laptops.
Lian Li Notebook Cooler Pad Model: NC-09 Black
Large 220mm 5V silent DC Fan with Blue LEDs, Large steel mesh allows extra air-flow under the notebook
The Notebook Cooler has dual USB connectors with one mini USB power connector which can accept either a notebook power source, or a Universal 5V USB Cell phone charger. In addition there is a on/off switch. The mini USB provides power to the fan and other USB connectors (Fan uses 300MA only).
The NC-09 cooler has a three level height adjustment, or alternatively the smooth base panel can conveniently be placed on a flat surface or on one’s lap. The NC-09 is perfect for High End notebooks, since Aluminum is four times more effective than steel to transfer and dissipate heat. The NC-09 has been designed for 12.1”/14”/15”/17” notebooks.
Dim: 400mm x 337mm x 34 mm (W,D,H)
Also, during gaming, remove the battery. The charging process generates extra heat and the absence of the battery will open up some extra air-space closer to the hot components.
You could try removing the battery even before anything else, fwiw. Let me know how you do... are you getting screen artifacts or what? I had a similar problem with several very expensive gaming laptops, so I don't mind offering some help since it was so hard to find someone with experience in fixing the issues.
Also, absolute worst case scenario, have you considered removing one of the GPUs or considered selling it to buy a desktop, since it never leaves your desk?