Gpu core clock frequency

I have a sapphire radeon 7870xt. It is supposed to run at 975mhz but whenever I start a game it only goes to 925mhz. Do any of you have any ideas on how to fix this?

Change it in the settings on the raedon control panel? Have you tried to do anything?

I have tried that. I have it at default 975/1500 but it runs at 925/1500. I disabled ULPS. It has only started since I moved to a 1080p monitor