The real test are the KASHIF_HIV type of WUs. They are the most demanding and will run a little hotter than any other WU on GPUGrid.
We could go through the whole process of suspending network activity in boinc, close boinc, make a copy of the boinc data folder, up your shaders, tuen boinc back on. if you get a driver crash you can close boinc, restore you backup (make another new copy) and start again. That being said, if you stick with 1478 I would just turn it on and let it run, no need to be nervous. Certainly open Precision now and again to make sure your not getting too hot (the GPU will automatically shut down before it burns itself out). Right ... set the fan speed manually ... crank it up to about 75% and see what temps your gpus get to.