Hi Russkly
I'm not sure what is causing the Event 41 Kernel Power error message.
I'm guessing it may be related to the GPU (graphics card processor) getting hot and tripping the power to the PSU. I'm pretty noobish with these things however.
My main CPU temps are fine.
I installed a (free) program called msi afterburner
http://event.msi.com/vga/afterburner/download.htm
This monitors your graphics card and allows you to overclock/change fan speeds etc. I mapped the fan graph in it to speed up to a higher RPM than it was before. This has stopped COD crashing/rebooting for around 10-15 mins. Before it was rebooting in game every 5 mins or so. The program also shows you how hard your GPU is working in game.