Hello everyone! I play on buying this build right now in December and my only problem that I am having is just buying the PSU! I am really not sure how much and which one I should buy so please, can you guys help me?
I do not plan on Crossfiring but if I do (on certain circumstances,) can you estimate how much it would need?
A system with two 6950s would do well to draw much more than 500W under a Furmark type load. So that means you could use a 550W unit (especially as you don't really plan to crossfire). But 650/750 would be the more popular choice to give you the option to crossfire and make sure that you don't stress your PSU beyond ~60% thus likely decreasing the possibility of fan noise.
I would discount the Silent Pro Gold as the whole series is know for having ripple and noise (12V and 5V rails) that is just about in spec at full load.
The Lepa IMO is unbeatable at $100, but there is the rebate to deal with...
If you are prepared to use a non-modular PSU then the Rosewill Capstone 750W is a very nice unit at a pretty good price.
If you do want a modular PSU and don't want to deal with a rebate then the winner is the Seasonic X-750.
I can't see any reason to get the more expensive Sapphire 6950.
I'd rethink the RM choice, those tall, toothy heat sinks are likely going to interfere w/ the cooler. The only cooling effect of these big coolers is that they "look cool". While they served a purpose (when they were effective) w/ DDR2, they are absolutely useless on DDR3.
At more than 2" tall in certain areas the Corsair Vengeance could pose a problem for users like me who use large coolers such as the Scythe Mugen 2. I was able to use the Corsair Vengeance only after I mounted the fan on my cooler on the backside. Size is definitely a concern with heat spreaders of this size and therefore I encourage users to check that they will have enough space under their heatsinks before purchasing the Corsair Vengeance kit.
The problem I have with the Corsair Vengeance is the same I have with many kits of RAM on the market. Companies insist on putting large coolers on their RAM and it limits the choice in CPU heatsinks that can be used within users system. DDR3 does not require these elaborate coolers with its lower voltages which translate to lower temperatures then RAM saw during the DDR, and DDR2 era. Corsair is correcting this with low profile versions of its Vengeance line but ultimately I would like to see the average size of coolers drop instead of having to look for specific low profile versions of a memory line.
Why does everyone suggest getting power supplies for future card add ons in a year? I would be replacing the ps with the other card to make sure the extra load doesnt kill the current ps and fry something else with it on the way.
You want to get a power supply with slightly higher wattage than you are running, as it will be good for future builds and it gives you headroom in case you want to overclock anything or add anything such as extra fans and graphics cards.