Dell Studio 1537 - ATI Mobility Radeon HD 3450, too low clocks.

Hi everyone. I don't speak english good,but i'll try to find some help here.

My Dell Studio 1537 have HD3450 graphics card, but it works on very low frequencies (250Mhz core, 247Mhz memory). It doesn't should be 500Mhz/500Mhz? 

When i try to OC, core gets 50% less frequency again (from 250 to 125 for example).

I tried all Dell drivers and some ATI with MobilityModder, and still nothing. Without drivers, it shows 250/247 too. So it isn't driver managed.

Ofcourse, i'm running Max Perfomance settings, and pluged in cable. With max battery life, frequency is 150 Mhz....

It can be GPU Bios error?

Please help :).