What is the total wattage draw of the GPU's & MB and the rating of the PSU(s)?  As a rule of thumb, you don't want to exceed 80% of the PSU capacity.  Also may need to check circuit this on and make sure it isn't being pushed beyond 80% -ex, if on 15A ckt, then W= A x V, assuming 120V, then Watts=1800 and 80% of this= 1440W.