Besides which, at stock settings there shouldn't even be a question of voltage being brought into the conversation. Since this has happened from the start, with no chance to have overclocked anything, there's no chance, at all, that it could be voltage related. Even if it was an issue with too high of voltage settings, it would only present itself under load conditions and would take much longer to reach those temps if the heatsink was mounted correctly, was pasted properly and the fan was working.
Make sure you have applied no more than about half a chocolate chip worth of thermal paste, that the backplate is firmly, but not too firmly, attached, and that the mounting brackets on all four side are fully seated. It's very easy to not mount the cooler correctly or overlook something. Take it apart, re-read the instructions, look at a few online video tutorials of installing that cooler, clean your CPU lid and heatsink base with thermal paste and start again.
Also, make sure you removed the plastic protective slip from the heatsink base. Usually they come with one, similar to the protective plastic you see that comes applied over the plastic on displays and televisions.