No response from keyboard to enter bios

when i power on my pc foxconn logo then press del for setup f7 for boot.
but no response from keyboard to enter bios.

when i remove single sata hdd cable , power on time able to access bios via keyboard. message boot from dvd drive .

Mobo is Foxconn H61 mxt1 f2 sv 7.04.1197
Hdd seagate baracuda 7200.12 500b
new cmos battery

kindly assist me to resolve this problem.

thnks and rgds
.