Today they finally deliverd me the second 7950. It's a bit different from my previous one. It has some kind of metal bridge for support over the top and it has two pci-e connectors from which one is 8-pin (my older one has two 6-pin connectors). I think this has something to do with lower voltage settings of the new card...
Here are some screens:
and 3DMark Fire Strike score (my previous score with single card was 7694)
I chose XMP profile in BIOS so my CPU is overclocked at 4600MHz and RAM at 1600MHz. Everything is working fine on my 700W PSU. I've asked around, done some calculations and come to conclusion that my current rig needs around 550W of power, so I have plenty. I've learned that people tend to overreact when it comes to PSU needs.