AwardBIOS MB DFI AK70 Problems

Hallo,
I have problems with my MB DFI AK70 to install a video card. Always I restarted my PC with Power Off/On BIOS cannot identify the video-card. The screen is black, and there is a continuous beeping at the PC. To clear this problem I mustclear CMOS. After this procedure I can restart my PC, with a BIOS errormessage : CHECKSUM error and further with the messages: Continue with
F1 or DEL to SETUP. If I hit one of this keys I can work with the PC. I had install a new battery. If I restartet my PC without power off/on (reset key) I have no problems.
Who can help me? Thomas