Well, run this https://unigine.com/products/valley/download/
or this
http://event.msi.com/vga/afterburner/download.htm (it is the MSI afterburner and Kombustor download, Kombustor is what you want)
and if the first card gets above 81, then you have issue. I am assuming you know software to monitor your GPU temp (something liker afterburner or HWmonitor). If not I can post a link to them.
If your temperatures get to be undesirable. Try EVGA PrecisionX and see if ramping up the fan speed does anything (its worth a try). Also if this doesnt work, consider getting something like the NZXT Kraken g10 for each of your 770's and use that.