Onion, you could use a 3rd party utility such as Afterburner, nVidia Inspector or eVGA Precision to set a custom gpu fan profile. Maybe increasing the fan speed will help with the cooling issue. The only thing that could be causing the throttling is gpu temperature or adaptive performance settings.
It might be a long shot, but maybe a laptop cooling pad could help too.
At the temps you're talking about, your cpu and gpu are dumping a ton of heat into a very small enclosure and you've got to figure out some way to help alleviate that problem (IMHO)