Well for starters, you didn't even try the other settings (LV, ULV, XLV) and jumped straight to the end on the least likely to work preset. "Ideal" uses lower voltages than the other presets, it's most likely to introduce instability if your chip doesn't have very good overclock yields. Try the ULV or XLV config for starters and set the min/max to 250/850 and see how it works like that.
ln -sf /usr/share/kernel-power-settings/ideal /etc/default/kernel-power