Seeing the odd spike up into the 90's is ok, but sustained temperatures in this range (and spikes approaching 100c) are definitely not safe. First thing I would look at is the fan speed control configuration (typically done in BIOS Setup, but some vendors also provide Windows tools for this). You want to ensure that the processor fan/blower/pump speed is increasing as temperatures increase and should reach 100% duty cycle (full speed) at your processor's Tcontrol temperature. Your processor's Tcontrol temperature will typically be somewhere between 80c and 85c. If you don't have a tool that can display your individual processor's Tcontrol temperature, just use 85c.
Hope this helps,