If it's one GPU on your main rig, then it's sharing it's resources with everything on that computer. The other thing is it could be overheating or if the power limit is too low. Either one of those will cause hash to start normal and then decline as both will lower the core frequency. What are your afterburner settings? What are the temps? Are you watching videos or anything else taxing the gpu? Is the CPU taxed? How much RAM?
Thanks to you and Smoreno for the response. Turned out to be an Awesome Miner setting. I had selected all of the individual miners in AM to autostart...cause that seemed like the thing to do. So basically all 4 cards I have were starting their own miner and the command line windows were reflecting basically 1/4th of the actual values. Turning off the autostart for 3 of the 4 cards in AM leaves me with only one window and the correct values. Lesson learned.