If you are crashing at 3.9-4.0Ghz with 1.35 volts, the most obvious solution would be to raise the voltage. AMD chips are fine up to 1.55v max for air cooling. Just be sure you closely monitor temps at higher voltages.
yay finally got it stable
i ran a load test and a stability test and both came out great
currently @ 4.2Ghz with 1.45V 21X multiplier
on the load test, im not sure if it just wasn't a good test or if my cooling is somehow amazing but i was constantly @ 18 C
the test was heavy load, is there a better one?
my idle temp is 14.5 C