Computer Upgrade Uncertainty

So, today is the day I get to make the first upgrade to my computer and I'm a little concerned about a few things; mainly fucking something up while I'm inside the things guts and killing it, but also whether or not the new parts I want to install will even work. Since the latest graphics cards are so affordable I thought I'd go for one of those and make my machine a little future-proof and maybe give it a new power supply to allow for that. Other than that though I'm not sure what else I may need to upgrade. I MAY need to upgrade the motherboard, but nothing I see tells me that it's absolutely necessary. With all of the virtual tests I've run with various pieces of software and all of the research I've done in the past few hours, sloughing through forums upon forums of questions and reviews, I don't really feel comfortable yet, so I thought I'd ask a community I AM comfortable with.

So, before I throw my specs out there know that I plan to introduce a GTX 1070 and an 850 watt power supply to this little guy. Are there any incompatibilities here that I'm not seeing?