I am database server programmer expert. I know the network and calculation stuff. It is the photons trust me on that. It was not your machine, it was how the data was split into 2 machines. The photons is very difficult to share data with PCs. The Master PC is supposed to handle all that and give specific photons axis data to the node PCs and it is supposed to calculate with and send the photons axis data back to master PC. Other possible theory, the other node PC was busy with a checker and other node pc missed some of the photon datas when it completed one of checkers ahead of others. The master PC was supposed to pause until all the current checkers are completed to send the photons back to master PC to redistribute it. It won't matter if you bought PCs with same speed because there are chances that one of the pc will get delayed. So I think that all the PCs need to have photons precalculated before it may start rendering with true colors on surfaces. It probably will need 2nd renderer engine for color and photons separately.