OOkkkkk ...
If its IDE and its not finding the drive within the bios (only flashing trying to detect it) then its not plugged in correctly, theres no power to it, or its set wrongly (slave / master)
1/ make sure the cable is connected correctly, if IDE, the red wire should point towards the POWER connector on the hard drive
2/ verify theres power to it
3/ check the master drive (usually the FIRST hard drive. bootable pc drive... windows etc) has the IDE plug from the CENTER of the IDE cable, (NOT the end- The SLAVE drive should connect to the very end of the cable) ... eg >
`Motherboard---------------------Master----Slave`
Note the length of the IDE cable from the motherboard to the Master is longer than from the master to the slave.
4/ check the second drive is set to slave- if you still have problems, take out the jumper to enable "cable select" which I think means it trys to automatically detect which one is it.
5/ If theres no luck, connect the Hard drive to the motherboard using another cable (there should be 2 IDE cables, if not, plug another in!)- per mobo, theres usually 2 sets of cables, each capable of controlling two hard drives each