If its an over voltage problem, then a resistor would solve that. Another killer of LEDs is voltage ripple.. especially spikes... nice smooth DC supply required.
You either completely smooth the voltage, or drop it slightly to UNDER supply your LEDs to lengthen life.
Best quality LED module ( used in signage) come with a current regulator IC in the package to ensure a smooth steady supply. The LEDs do last longer this way, but youll find that theyll be lovely and bright to start with and then just drop back to a certain level of decay and stay that way for quite a while. No one is getting the promised 50,000 hours out if them... more like 5,000 ...
