The hard drive cable extend my MBP's life
The hard drive start to have several issues after 4.5 years use:
1. The system start to freeze more and more frequently during normal load, need a hard reboot to get it back to work.
2. Reboot could freeze. The only workaround I found is to hold down option key to let the system stay in boot drive selection screen for more than 1 minute, then press enter to continue booting.
3. Upgrade MacBook Pro EFI Firmware Update 1.7 will more the system freeze even more frequently. I ended up downgrade the firmware to 1.6. As a result the SATA speed stuccoed at 1.5Gb, instead of 3.0Gb of the 1.7 version.
4. Tried upgrade the built-in 250GB hard drive to a bigger one several times (500GB, 1TB), only to get a more unstable system. Ended up come back to use the old built-in drive.
I searched around and found someone who had the similar issue fixed it by replacing the hard drive cable. I felt it kind of intimidating, thought it could turn my unstable machine to a complete dead one. Until recently I decided to give it a shot, worst case is I will by a new MBP and kiss goodbye to the old buddy. Guess what? The system works like a dream under heavy load for more than 24 hours! And I can finally use a 1TB drive in my MBP. Thanks ifixit!
Just follow the ifixit instruction, you won't get it wrong.
P6 Pentalobe Screwdriver 2009 15" MacBook Pro Battery
MacBook Pro 15" Unibody (Mid 2009-Late 2011) Hard Drive Cable