Can you try single GPU setup and benchamrk both cards with Furmark burn in? It is probably bad GPU. Experienced that in the past with your symptoms and Nvidia GPU.
Before I go about this I just have a question: are you saying you think both my GPU's are bad? although normally only one has temps in the 80s, the other is still high 70's (78, 79). Also what exactly might be bad with the GPU? It seems to function and idle just fine.
Thanks for the reply!