For those, who need comparison data.
version 7 speeds:
7870 - 95 sol/s
7950 - 145 sol/s
7970 - 165 sol/s
270x - 100 sol/s
280x - 165 sol/s
285 - 110 sol/s
470 4Gb - 155 sol/s
Couldn't be more accurate. You can add
290 - 200 sol/s to complete the list
295x2 shapire - 452 sol/s to complete the list
I listed only results on GPUs that i have, it won't be apropriate to add something because results may be different depending on settings (all stock, but bios mod timings), rig hardware (i have most rigs on 775 socket, even some with DDR1 memory,after V3.0 they show same speed as the new ones on 1150 socket).
If anyone interested i came to conclusion that only thing that matters for old CPU on multiGPU rig is HyperThreading or other VirtualCore technology, without it there is a big hashrate drop.