The b250 motherboard can be equipped with a GTX1060.6G graphics card or GTX1070 stand-alone graphics card.
Intel B250 high-speed chipset for Intel LGA1151 processor and DDR4 system memory. It comes with a DSUB and DVI video output for the CPU's built-in Intel graphics display, and if you don't rely on the PCI-E lift board, there are two additional on-board 4-pin Molex power connectors (which I don't think will do much for 12 cards) that you can skip regardless of. The rest are very standard configurations, but we should note that the motherboard doesn't seem to have an M.2 slot, so there's no extra 13th GPU to choose from or use for M.2, SSD drives and extra features.
B250 motherboard supports all PCIE interface independent graphics cards, high-end GTX1060 1070 1080 graphics cards are no problem, GTX750ti not to mention, absolutely supported, the CPU is best i3 7100 dual-core four-wire, I5 7500 quad-core is the best,
B250 motherboard, can be equipped with GTX1060 6G or GTX1070 independent graphics card, quota of power above 450W can be.