2nd ide hdd not detected by os

Guessing, but it sounds like your hard drive has been damaged. You may need a new drive, or at least repairs. If you have a "rescue disk", give that a try.

1.FIRST YOU DO ONE THING IF YOU USING XP OS MEANS CHANGE THE SATA MODE TO IDE OTHER WISE CHANGE THE SATA MODE TO AICH.
2.IF BOOT WITH CD MEANS CHANGE BOOT PRIORITY CD/DVD ROM
2.IF YOU BOOT WITH HDD MEANS CHOOSE HDD.
BIOS OPTION----CONTINUOSLY PRESS F2 KEY.

SHUT DOWN COMPUTER AND CLEAR CMOS BY RESETTING JUMPER ON MOTHERBOARD AND THEN RETURN JUMPER TO NORMAL POSITION OR USE RESET BUTTON. UNPLUG ALL HDD SATA CONNECTORS FROM HDD. BOOT COMPUTER TO BIOS. MAKE SURE ENABLE ALL SATA IS ENABLED, PRESS F10 AND EXIT.YOU WANT TO SHUT DOWN AGAIN. NOW REATTACH SATA HDD AND CONNECTORS AND BOOT TO BIOS AGAIN. NOW HIT F10 AND LET COMPUTER RESTART AND LOAD INTO THE OS. LOGON AND CHECK DEVICE MANAGER..SHOULD BE THERE. IF NOT CHECK MOTHER BOARD WEB SITE FOR BIOS UPDATE. IF BIOS UPDATE DOESN'T DO THE TRICK, SHUT DOWN AND DISCONNECT THE IDE DRIVE, UNLESS IT CONTAINS YOUR OS. TRY BOOTING TO BIOS AND CHANGE ORDER OF 1ST BOOT OPTIONS, HIT F10 AND EXIT AND ALLOW COMPUTER TO BOOT TO OS, THEN LOGON, GO TO DEVICE MANAGER AND REMOVE IDE AND RESTART, ONLY IF THIS HDD DOES NOT CONTAIN OS. YOU SHOULD BE FINE AFTER THIS, OR INSTALL YOUR OS ON THE SATA HDD.

you change Boot sector set HDD

Shut down the computer.Disconnect the ide cable from hdd .Just connect using primary hdd and boot the computer. Shut down the computer. Connect the secondary hdd both IDE and power cable. Restart the system and go to bios . Check if the both hdd are detected in bios. If detected boot to desktop. If not detected reset bios settings to default.Restart computer and check. IF still not detected shutdown computer.Disconnected secondary hdd and primary hdd,connected secondary hdd to primary ide connecter and check in bios. If still not detected try connecting secondard hdd on different computer and check.

you will not be able to put os in the same hdd on a computer.also if vista is installed on one hdd & the other partition is on the same hdd so please try not to install 2 windows on same hdd,its not possible...

Initially check the connectivity of the cable, whether sata/ ide from motherboard to hdd., also do check in the bios., priority of the boot level whether your hdd is selected., in the first or 2nd., and also do check whther your hdd is detecting in the bios., if not your hdd got problem...

Try reversing the connections so the new drive is detected as the primary master.

go into your BIOS and on the bottom of your screen there should be a (last good config) of (fail-safe config) value for one or=f the F1 to F12 buttons. also. are you running a 4gb hdd??? or is that a typo? anyhow, XP REQUIRES 2GB at all times free if your hdd is running at less that that (cause its full) your boot up could be messed around. finally make sure that the little plug on your hdd is across the Master or cable select pins not the slave as this can cause probs too. good luck.

Have you tried the HD in another Machine? The HD could be at fault.