I'm wondering which one is more important when comparing HD 7850'sSAPPHIRE Radeon HD 7850 11200-01-20G
core clock: 975MHz (Std 860) / memory clock: 1200MHz (4.8Gbps)GIGABYTE Radeon HD 7850 GV-R785OC-2GD
core clock: 920MHz / memory clock: 1250MHz (5.0Gbps)
Will the higher core clock or the higher memory clock show a bigger difference? I will not be overclocking it and I have PCI 3.0 on my mobo.
Although you cannot compare cards like this to figure out which one is "better", all things being equal, core speed relates much closer to a difference you can actually see than the memory clock. As rule of thumb for instance when overclocking a GPU, you always work with core speed first to attain the best performance possible, then tweak the memory speed last to gain that miniscule fraction of a percent more. It may even be beneficial in your overclocking efforts to lower the memory speed if it will allow you a higher core clock and end up with better performance.