pull the MB out, sometimes filth can collect under the mb,   

if the mb is over all filthy wash it and dry it off with a compressor.

if the PSU is filled with filth , blast it out with a compressor.

or swap the psu with another machine.

just because some ram might work fine in other mac's doesn't mean its going to work fine in the q700.

take a picture of the ram simms that you are trying to install in the q700.