I am thinking of upgrading to the AMD FX-8350 and I feel like I would need a on par mobo to go along with it. I also just purchased the h100i to kick of the upgrade. I'm also very worried I'm most likely gonna have to purchase a new key for Windows 8.1 since the key is tied to my mobo (according to newegg.) Any recommendations or input on what I should and shouldn't be doing?
I have never heard of a Windows key being locked to a motherboard - I could be wrong but I call BS...
And yes out of your system the CPU and Mobo seem to be the best things to upgrade. Nothing wrong with the FX-8350 but I do not know your budget on a motherboard so I will recommend brands. Either Gigabyte or Asus, they both make really nice motherboards.
A key can be tied to hardware, mostly in Pre-built PCs. You just have to phone MS and tell them that your old motherboard died, and you had to replace it with a new one. They'll help you get the key working on the "repaired" computer. :)