I don't know what bios manufacturer makes your bios, but I found a mention of 6 beeps for AMI.
"6 Beeps - 8042 Gate A20 failure - Bad CPU or Motherboard "
Further research resulted in a more detailed description...
"The chip on your motherboard that controls your keyboard (A20 gate) isn't working. First try another keyboard. If it doesn't help, reseat the chip that controls the keyboard, if it isn't soldered in. If it still beeps, replace the chip if possible. Replace the motherboard if it is soldered in."
If you do have an AMI bios, here's are some possible fixes...
"You are getting 6 beeps indicating 8042 - gate A20 failure:
Check for foreign objects such as screws that may ground the motherboard and make sure the screws that hold the motherboard are not too tight.
Try reseating the keyboard controller chip (if possible).
Swap the keyboard.
Swap the processor. "
Another website had this to say about 6 beeps on AMI bios...
"8042 - gate A20 error - check the keyboard for loose or broken connections. This problem can be caused by a CMOS setting or bad keyboard controller chip."
Gentle