Help regarding Power Supply/Hard Disk

Salam to all members,

My PC specs are:

Processor - C2D 2.0Ghz

RAM - 1GB DDR2

Graphic Card - ATI Radeon HD 4650 1GB DDR2

HDD - Segate 500GB

HDD - Western Digital 80GB

DVD ROM - HP

Current power supply is A-open's which delivers 300Watts. The problem I'm facing is that after running smoothly for around 2 months, my 500GB HDD started shutting down while computer was running. I has happened 3 times so far in last two weeks. I got this one in replacement of another 500GB HDD which faced same problem and after a few times it never worked again. Now the new one is behaving in the same manner. I've disconnected my graphic card and DVD Rom and the result is that hard disk is running fine again and no shut downs.

My questions is that is there any problem with HDD? If not and the current power supply is insufficient then what should be suitable power supply keeping in mind my PC specs and that I play games and watch HD movies very often?

P.S. Someone is selling me Dell's original 400 watts power supply (used). Would that be good if Power supply is culprit?

Regards,

Recently load shedding burnt my power supply. i replaced it for Rs. 650

it is advisable to take your hard disk to a friends computer and let it run for a couple of hours and see if it shuts down there as well. or get it checked from a repair shop.

it looks like it is the power supply problem from what you have described here. Try to get a new power supply if you can. Second hand power supply are cheap but a risk. If you can, try to get a new antec/fsp power supply if you can.