You're better off with an R7 265. It's basically a rebadged 7850 with higher clock speeds. Retails for $150. It sold out within a few hours at Newegg this past Wednesday. Be on the lookout for when it comes back in. You'll want to pick one up before the miners get to it and cause severe inflation. If you can't manage to get one you're much better off going for an nvidia card. Currently all AMD cards are inflated.
and psu is best but i need a mobo with 2x 16x pci e slots and at low price am3+ atx mobo i have fx 6300 and cooler master n400 case cooler master 212 evo cooler WD green 2 tb and mobo should be of low price as is just do gaming mostly
1. 550W will not be sufficient for SLI/CF configuration
2. ASRock 970 Extreme 4 will get the job done and also be able to support FX 8 series in the future according to many actual experiences
3. Don't get WD Green unless it's a lot cheaper or you want to save a few watt
I did say that 550W won't be able to support SLI, but nor can the 650W. (unless we're talking about GTX 750 Ti or some other low power consumption cards). For example, I would say that 650W will be sufficient for a GTX 650 Ti SLI, but not for a GTX 760 SLI because their max TDP goes a lot higher.
Most cards with max TDP under 130 will be able to handled by 650W in a SLI config. Although that isn't saying that it will be power efficient, because most PSU are most power efficient when under 50-60% load.