Any chance you know which fan? Is it case fans or CPU fan?
Presuming they are running on auto to compensate for heat, it would be odd for a memory upgrade to increase it that much, unless your PSU is working too hard with the new RAM installed. If the power supply isn't up to the task it will start pushing out a LOT of heat until it finally dies.
Another possibilty is that you knocked something whilst fitting the RAM, if the CPU heatsink is a little off kilter then it may not be working as well as it was, and thus requiring extra cooling.
Also does it have good airflow inside, if you've been moving lots of wires around this can have an impact on temperatures, make sure all wires are bundled together and away from fans so the air can circulate.
See if you can find an app for your motherboard that displays realtime temps, many support it now, if its an older one you may have to wait until it gets hot then restart and quickly check the temps in Bios.
Feel your power supply, and around the case, see if anywhere feels hotter than usual.
If nothing works try changing back to the old memory and see what happens. If its fine then probably means either PSU isn't good enough or the new RAM is putting out more heat. If it still goes wrong then you've probably moved something or its too late to save the PSU.
There can be many reasons to be honest, memory timings, clock speed, etc. Trial and error is the best way to go. Does it kick in when using intensive software? Games and the like?
I tend to go with, If I can't smell burning it will probably be OK.....