The issue with Corsair GS series is that it doesn't go through the intense vetting of components as the other VX, HX and TX series SMPS's go through.
http://www.hardwares...ply-Review/1103, get a lower rated VX series SMPS if possible, even the Corsair VX 550W ~4500/- is a better deal.
Next, I flatly recommend you to steer away from the Cooler Master GX line-up [this must be the one shop keepers would have been pushing] and avoid the eXtreme Power series even more, the GX series has serious issues with load ripple suppression, read here for more -->
http://www.jonnyguru...=print&reid=188 /
http://www.hardocp.c...supply_review/9 /
http://www.techpower...W_Bronze/8.html.
[/color]
The eXtreme Powee series is worse than the GX line-up in terms of everything, efficiency as well as power out-put and the warraty is cut by two years to just 3 years of warranty.
I will rate performance in this order -->
Seasonic > Corsair > Cooler Master
After sales -->
Corsair > Cooler Master > Seasonic
The Seasonic after sales is looked after by Tirupati Enterprises and they are pretty reliable. They are the distributors and service providers for ThermalRIGHT as well as Antec coolers.
Hope this clarifies things, Cheers!!