Power supply for Litecoin mining rig I've been told my power supply needs to be of a good brand and have sufficient power for all the hardware, with some to spare. A 80+ gold PSU is more expensive but could be the best idea.

I'm starting out my rig with three SAPPHIRE VAPOR-X R9 280X 3GB GDDR5 OC for now.I'm looking to go upto 4 or even maybe 5 in the future.

The price difference between Silent Pro M2 1500W &amp; Corsair Professional Series Gold AX1200 is 42 USD from where I am to get it.One being silver rated and the other gold.

In terms of power efficiency and expansion ability of the rig which one would be better and why ?
For mining, it is a 'no brainer' to me to get the most power efficient PSU as even those meager differences of efficiency will pay themselves off in a pretty short time... that is assuming that the price of these 'coins' stays at their unusually high price anyway.