I just got my gpu yesterday, tested it by using in p3d(flight sim) and the core clock jumping between 850-1950mhz. Is that normal? It cannot be thermal as it hardly reaches 60c and gpu usage is 20-60%. It is strange for me as my previous gpu hd7870 had always had constant core clock. I not touched the gpu,nothing is changed in afterburn. Any idea why is this? Thanks