I thought it might have been a lower VRM power phase for the biostar, but it the gigabyte is 4+1 just like the biostar.
Maybe it's the 2oz copper and choice of capacitors that allow the gigabyte to OC higher?
I have a gigabye ga970a-ud3 with 8+2 VRM phase. When upgrading from my previous motherboard, an MSI 890GX w/ 4+1 phase, I was able to OC my northbridge 200MHz higher to 3GHz using the same voltage. My CPU also OC's higher now but I left it at 4GHz because it's fast enough for my needs.
If the power isn't being delivered as 'cleanly' as your old motherboard, your only option is to increase voltage for stability and deal with the increased heat.
Also, you MUST do a reinstall if you are changing motherboards. A motherboard is like a tree and other components are like branches. You can switch out branches without windows freaking out but replacing a whole tree and expecting the old branches to grow is ludicrous.