Internal hard drive not recognized by Macbook

I am facing a very unusual problem with the Macbook which I am using. Recently i replaced the hard drive of the Macbook as the old hard drive was damaged. After replacing the hard drive, I installed Mac OS X Snow leopard on it and everything was working fine but the problem is that the Internal hard drive is not recognized by Macbook, it only detects the new hard drive only when connected to USB port. I really dont understand why this is happening and need your expertise in solving the problem. So if any of you knows how to solve the issue, please suggest some solutions.

There is battery located on the logic board of the Macbook which is responsible for saving all the settings which are required for booting. Open the Macbook and locate the battery on the logic board. Remove the battery and check the voltage across the battery using a Digital multimeter. The voltage of the battery should be between 2.5 volts to 3 volts. If the voltage of the battery is below 2.5 volts then the macbook is bound to give such problems. Hence replace the battery and see if the Macbook is detecting the hard drive or not.

All the Apple products are covered with 1 year apple warranty which is applicable if the product has not been damaged physically. Therefore I would suggest that you take the Macbook to an authorized apple care center and get it checked by their technician. The technician at the apple service center will check the Macbook thoroughly and list all the problems with it. If the Macbook is under warranty then the Macbook will be serviced for free, if the Macbook is out of warranty then the service charge along with the cost of hardware replaced will be levied.

The possible problem could be with the connector of the internal hard drive. If the connector of the internal hard drive is not proper then the communication between the system and the hard drive will not be proper and sometimes may lead to hard drive not getting detected. If you can open the Macbook, open it and check if the connector of the hard drive is working properly or not. You can connect a good known hard drive to the internal connector and see if the hard drive is getting detected or not. If the good known hard drive is not getting detected then the internal connector is faulty.

All the functions which are performed by the computer are controlled by the logic board of the computer. Logic board of the computer is responsible for providing correct voltages to all the devices which are connected to it and also for taking logical decisions. Hence if the logic board of the computer is faulty then the computer will not work properly. Hence get the logic board of the Macbook checked by some expert. If the logic board is faulty then you will have to replace the logic board.