OK I reread your post where you say
"if i disable de onboard chips but i still do not have a new graphic card..how do i enable back my onboard chips?"
And the answer is;
You need to clear the CMOS to reset the BIOS back to its default settings. Normally your motherboard operates with the clear CMOS jumper on pins zero and one. You can clear the BIOS by removing the battery and moving the clear CMOS jumper from pins zero and one to pins one and two. Wait five to ten seconds and move the jumper back to pins zero and one and reinstall the battery. If you don't have a clear CMOS jumper then don't worry about it. Taking out the battery for five or ten minutes usually clears the BIOS.
Sorry about the late post; I should have answered your question the first time.