My plan is to sell the 6870s and have a 4 card rig of 7xxx, maybe two 7950 and two 7970. I'm guessing I'm going to want at least 1100W here? What's the most cost effective way to try and get those extra 350w?
Should I try to power 3 cards with the 850w and buy a 300-400w for one card? Sell the 850w and just buy a bigger PSU?
The PSU stuff for cards is something new to me (hell I never even owned a dedicated graphics card until I wanted to start mining) so any advice will be appreciated.
The more watts, the more money getting a replacement is going to cost. Use the 850 to power 3 cards, then get another to power your mobo and another card.
850W is not enough for 3 cards. He'lll need 2x 850W or 1x 1050 + 1x 850 to be safe.
To OP: No, what you want is to buy 1x 1050W and run 2.5 cards on that and 1.5 on the 850W. Setup will be rock solid and run close to max efficiency.
2.5 + 1.5 cards...Is it possible for the two power cables on a card to come from different PSUs?
Anyways adding a 1050w to my 850w sounds nice, but I'm going for cost-effectiveness here. A 1050w is expensive as hell, and I feel like I gotta go Gold because it'll save me money in the long run I think. If I'm going to shell out the money for a 1050w, I might as well sell my new 850w and just buy a 1200w or something.
Yes it's possible. I'm running like that right now.
Trust me. You don't want to stress the PSU. Better go with 2 @ ~60% load, than with one @ 90% load.
... Cost me a Hell of a lot less upfront over other options, though. They were on a great sale.