ICH/MCH Over-heating; and possibly a dying motherboard?

Before questions arise about my /Specs/, here they are:
Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz
nVidia GeForce GTS 450 (EVGA, Super-clocked.)
4 GB of DDR2, By G-Skill.
Intel DP43TF Motherboard.

My Motherboard is roughly a year old, or so.
My problem in detail:

Recently, I've had really bad performance in PC games (Modern Warfare 2 was recording 40 or so FPS while in a battle, before the random performance drop it was running at 80-100 FPS; same settings. I can supply more information on what games, if need be.) ; then came bad performance period. I turned on Speedfan (4.42) to see what my temperatures were, YESTERDAY. My CPU was running at 99C, both cores. I quickly turned my PC off, un-plugged everything and turned of the PSU. (500 Watts) I pulled my motherboard out, slid the heatsink off. I removed the last layer of thermal compound and applied new. Re-seated the fan after doing so. I then placed my motherboard back into the case. After plugging up everything as it had been before removing the motherboard, I turned it on. I pulled Speedfan back up from my desktop and it recorded:
ICH: 69 C MCH: 59C. My CPU was idling at 34C, both cores. I had applied/plugged in everything correctly. It's recorded the same numbers, right now.
I'm using an Intel motherboard. I have never OVERCLOCKED this CPU, ever. Could it possibly be that Motherboard is in fact, dying? Do I need to replace the battery found on the motherboard? It has seen over a year of use. I can't think of a possible answer to this slow-down in performance. I've done multiple malware scans, virus scans, and even defragmented all of my hard-drives.

Another detail, I'm using the stock heatsink. It had never let me down before. A large fan in the back of my case, along with a smaller, but faster fan on the side of my case.

I will supply more information if needed. Thanks.