Gtx 770 overclock wont go over 1058Mhz

[Julius_16]

I'm trying to overclock gtx 770 with gpu tweak 2 and when I apply my overclock clock speed goes to 1058Mhz. It's normal clock speed is 1100?? help

 

[Julius_16]

Edit: its so low because I was not using any app in fullscreen and when I did the overclock came on