Replacing a laptop's internal 2.5" HDD with a 3.5" HDD

For the past few months, my laptop started freezing randomly. At first, I suspected the windows operating system. So I installed ubuntu to see if it really was a windows problem but I got the same problem in ubuntu. Just to make sure, I tried using the same hard disk on a differenet laptop and I got the same problem again. So I decided that the hard disk was the culprit.
Now I thought I had to buy a new hard disk to solve the problem. But suddenly an idea struck me. I had a PC which had some problems with it's mother board and it had a 3.5 inch hard disk in it. Considering that both the laptop's hard disk(2.5 inch) and the 3.5 inch hard disk from the PC used the sata connectors, I thought why not use the 3.5" hardisk with the laptop.So here's how it was done.

At first you would think a single piece, 22 pin connector like this would do the job.

But there is a problem. The laptop supplies only 5V to power up the 2.5" disk but the 3.5" disk needs both 12V and 5V. So I had to use a different approach

Note:

• If you want to use a 3.5" hdd as an external hard disk, you can just use an external case and connect it through usb but then you wont be able to use it as the primary hard disk of the laptop because firstly, windows cannot be installed on an external hard disk directly(it can be done through VHDs) and even if you could, the overall speed will be very limited. 
• The 3.5" hard disk won't fit inside the laptop, so the 3.5" hdd will have to be kept outside and you won't be able to move the laptop around.
• The voltage provided by the laptop to power the 2.5" disk is not sufficient to power the 3.5" disk. So you will have to power it up somehow externally(I am using a PSU).

In my case I was already using my laptop as a pc because it's monitor was not working and I was using an external monitor. So I didn't have to worry about portability anyway.

Connecting the data port of the 3.5" HDD to the laptop:

To connect the 3.5" data port to the laptop's data socket, you need a female to male sata adapter but the most common ones that are available are the female to female adapters. I searched the local computer stores and the internet but couldn't find one so I had to improvise one from a female to female adapter that I had.  I used a small saw to cut out the part shown in the picture. The final result looks a bit ugly but now we have a female to male sata data cable!. 

Making a male connector from a female connector.

Powering up the 3.5" HDD:

Now we need to give the hard disk power. Like I said earlier, the 5V supplied by the laptop is not enough. So we need an external power supply. I found that the best thing to do was to use the PSU of the same PC from which I took the 3.5" HDD. So I unscrewed the screws which held the psu to the chassis of the PC and took it out. It looked superfluous to use a PSU just to power a hard disk but I couldn't think of any other option.

ATX power supply unit

There are a few things to note here. Just plugging in the psu to the mains power supply and turning it on there won't really turn the psu on. One more step is needed. We need to connect the green pin called 'Power on' in the ATX power plug to the ground(any black pin). Use a thick wire to connect them so that they stay tight. In a PC this connection is made through the power button.

Connecting the 'power on' to ground.

We are almost done. Connect the HDD's data port to the laptop's using the male to female data connector and connect it's power connector to a sata port of the PSU.

Final connections.

We are done! Turn on the psu and then the laptop and it should boot.You might have to do a fresh install of windows or any other OS.

Update: I have been using this setup for 6 months now and it's working perfectly.