Realbench will utilize all GPU'S it finds in your system regardless if they are in SLI OR crossfire. it will even use the IGPU if there is one so make sure you enable it. I have run the openCL test both ways and did not see a difference in the score. only by adding GPU'S did the score increase. The openCL test dose not contribute much to the total score as say the multi tasking or video encoding. If you want a high score you need high CPU freq. and fast tight memory timings. also read the realbench tweaks thread that will add points to your score for sure.