Speedfan is crap. Your core temps are 82,81,78,77. These are to hot, your asking for trouble. To be perfectly honest HWMonitor actually reports the temps a little low on the Max. value. I use RealTemp for everyday usage as it tends to report a higher value which I feel is more accurate. When I'm helping, I ask people to use HWMonitor as it supplies me with more info than RealTemp.
You should drop your speed back down to 4GHz, I would. What heatsink are you using?
Can you supply a link to the exact memory you have? I looked at what you had listed in your 1st post and the speeds I found said 8-8-8-24. If you lower these to 6-8-6-24 your memory controller will have to work much harder and require more voltage. Since the memory controller is built into the cpu it's going to run hotter still. I would definitely lower the cpu speed back to 4 GHz before I tried 6-8-6-24.