1. I accidentally broke one of the four pins of the CPU heat sink fan (the one with press and turn) which gets inside the motherboard while installing it. it is working on three pins right now. should i replace it or leave it as it is. and if i need to buy one please show me the right choice.
2. I bought a cooler master k380 cabinet some days back replacing my 5 year old local cabinet. but the psu wires of my previous cabinet is short for the power connector of the motherboard. I need a good smps with more extension chords and longer cable at an affordable price which can run 650 ti gfx card in future.my budget is rs 3000 ( 50$). my preference are corsair and coolermaster as I am from India and the latter is more available
You can just buy an extension cords for cheap that'll be just fine
And download piriform speccy http://www.piriform.com/speccy/download and see what temps you are getting on your CPU. If you're staying in the 30-40 degree range at idle and not going above 70 or so at load, you'll be fine (though I would still recommend replacing at some point)
The Cooler Master Hyper TX3 is a good, cheap alternative that will even run quieter, too. When you get a chance to upgrade, that may be something to look at.