Its not as much boards fault but poor CPU, at extremesystems forum there is batch thread , some got lucky with very good CPUs doing ~5ghz with low volts <1.4 others got poor ones requiring high volts ~1.5 for same speed.
Anyway general consensus is these new sandy chips are very robust and can take volts and clock high. Surprisingly they don't work well under subzero temps
but under air and water they go.
Some even tried to kill em doing 1.6volts hitting 98c and CPU still working strong
Anyway time will tell , ill be using this 24/7 as it is stable and there is still more headroom given more air.