It has a TDP of 140.
There are several reasons why this could be happening. Biostar isnt the best quality, and ASUS is really good quality. The 970 vs 990 chipset can also be causing problems. So can the cooling involved, even if they are identical coolers, the thermal paste might be applied different.
You also could be a victim of the silicon lottery. Certain chips hit their limit, others dont for a few more GHz.