LGA775, it's got a dual core Pentium on it, latest bios. I'm running 2 risers to the 2 PCIE slots with some 4GB RX480s on it, getting around 26 Mh/sec on each heavily underclocked on the GPU and undervolted, pulling around 325 watts at the wall. Not ideal in any case, but it's an old box and it works and slightly spreads my risk across 2 systems in my hobby mining farm. Windows 10 Pro, 6GB of RAM, I was initially running it on 2GB of RAM with sgminer, had to get over 2 to get to Claymore which is what I run now.
I have another rig that's much more modern, one of the Biostar LG1150 boards, but like Phil said give it a shot with 2 and see. One of these days I'll move one of these low end cards to that other rig to see if it mines a little faster, but I'm making that tradeoff of having my stuff split between systems so something is always up and mining when I'm tinkering or having a stability problem.
This motherboard was once my Home theater PC. I've been proud it hasn't hit the recycler yet.
