I was wondering if it is possible to reduce my AMD Phenom II x6 1090T BE from 6 cores to 2 cores. I currently have it a 4 cores but I would like to reduce it to 2 cores to see if I can run Guild Wars 2 with better performance. I didn't want try it out before I ask others who know about these kinds of things. Thanks.
Why would disabling four cores help performance?
The only benefit of disabling cores would be to allow for a greater overclock or to allow more L3 cache per core.
The likely result of your experiment will worse performance.