Well there is a lot of things to consider while buying a PSU. But the most important being the kind of system you are going to run with these. If you are planning to run a Sli or a crossfire system (judging by the wattage range you are looking for i hope you are, cos if not then 650w is a huge overkill and plain waste of money), now supposing that you are then i would suggest going for a multiple rail PSU, in your price range the PSU i would suggest is the Antec TruePower New 650w.
It would probably cost you around 6200/-, just 200 above your budget, Also remember that while considering a PSU, stuff like PSU efficiency and one being gold, silver or bronze certified is all bunch of Bull sh!t, it doesnt mean anything and all it accomplishes is reducing your monthly electricity bill by a few bucks, and that's it !!!!!!! there is nothing more to it, so don't get blinded by the Gold, Silver, and bronze bullsh!t
While looking for a PSU you have to look at test results conducted under real working conditions for VOLTAGE REGULATION, RIPLLE EFFECT, COOLING and last but not the least theBUILD QUALITY of that particular unit, according to the reviews Antec is a winner there with Seasonic X series topping the charts especially the Seasonic X 650w, which unfortunately is nowhere to be found in INDIA.
Between the units you mentioned and the one I suggested, Antec beats both of your units in almost all of the 4 criteria's, while remaining well within the required margins as well as in using top quality parts for their PSU's ( FYI: Capcitors made in JAPAN are among the top of the line capcitors anywhere in the world, i believe Corsair AX unit's have them). Also do understand that Seasonic makes the PSU for a lot of companies including corsair, so under the hood both these PSU's have the basic hardware made by Seasonic only, Corsair just puts it's label on them.
Now you must be wondering that why did i use bold letters to highlight build qaulity?, well that is the answer to the question you asked.
To reduce costs these companies use different quality capacitors and other electronic equipments and then divide their PSU's into different series such as HX, VX, TX, etc in case of Corsair. So beware of this fact while looking for a PSU, and that is the reason why there is such a price difference between their different series as well as their warranties ( Lower the build quality, Lower the warranty period offered, It's plain Common sense ).
Every company including Antec, Corsair and all the big names in PSU manufacturers use the same cheap way to extort money, so what you have to look while buying a PSU is also the warranty being provided. Antec is providing a 5 year warranty on the TP650w and if you were to ask my opinion, this unit beats both your above unit hands down in all departmenets, plus it secures you for your crossfire or SLI configurations in the future with it's 12v multi rails rated at 25A, 25A, 22A, 22A, which i am sure you would want to overclock and that's where multi rail will win over any single rail PSU.
Also i hope you do realize that even a 500w PSU is enough to run a highly clocked SB rig with a single GPU and multiple HDD's, Also just for your future reference, in a PC, the GPU, HDD and the Processor are the most power hungry components, the rest consume very little power, so if you are not going to go SLi or Crossfire in the near future, i wouldn't advise you to buy a 650w unit, cos that's just money wasted which could have easily gone towards other important aspects of your PC configuration. Just keep this in mind while deciding on a PSU, rest is upto you.
Hope this helps !!
