The max user internal CPU temp for the FX-8000 CPUs is 61C. Beyond that you can start seeing errors in the mid to upper 60's. There could be a couple reasons why the temp of the CPU increased. Hopefully you are using an applet that reads the FX CPU internal temp properly in the 60C-70C range such as AIDA64, Core Temp, OCCT or HWiNFO. Some applets do not read the CPU internal (core temp) properly or show the socket temp as "CPU". The socket temp can run 10C-25C higher than the internal CPU core temp depending on load and duration..
The new GPU card can produce more heat and without sufficient airflow thru the case that heat can heat the air blowing over the CPU. If the GPU vents out the back of the case then you need to make sure it can do so freely. It can help to remove some of the slot cover plates to allow hot air to escape more easily depending on your case design. The new GPU might also run the CPU under more load for faster graphics. The OE AMD box fan cools just fine as long as you have proper case airflow and CPU vcore. You can use applets like OCCT to record critical parameters such as CPU temp, frequency, vcore, etc. under load to determine what is happening. Make sure that the fan speeds set in the BIOS or O/S are set to full speed / 100% so the fans can run at there full speed under heavy loads.
Some mobos do not regulate the vcore voltage well under heavy loads on 8-core FX processors. OCCT can show you if the vcore is running too high under load. Most mobos have a vcore adjustment to try and stabilize the vcore voltage under heavy load known as Load Line Conditioning (LLC), or similar. You may need to try all available vcore stability settings to see which one holds the voltage closet under heavy load to the default CPU vcore for your processor, which is typically displayed in the BIOS.
You might find the FX-8350 temp thread below useful.
Slap on a Corsair H80, that'll keep it more than cool and keep it quiet while it does so. Remember that a more powerful GPU eliminates a previous bottleneck, meaning the CPU can work harder than before.