logainofhades :
A 7850k is nowhere near the GPU performance of an R7 250 which is pretty much an HD 7750. It is about on par with an R7 240 at best, which is slightly faster than a 6670. Not to mention the better upgrade path on the Intel side. On the CPU side, a 7850k won't compete with an i3. A 750k @4.3ghz couldn't beat an ivy i3 in games. Kaveri is not going to fare any better against Haswell.
I'm tired of hearing about intel. they arent in the APU market, and they just dont compete with AMD's FX series in terms of Price to Proformance ratio.
The 7850k, however, has ups and downs all its own. Needing higher ram for faster proformance leaves you at a new budget consideration. 2400 Mhz and higher speed ram cost some big bucks, with a pair or corsair vengeance pro 8 GB ddr3 2400Mhz CL10 chips costing $250+. The proformance cap seemed to be at 2133Mhz in early tests, but once people got the balls to test 2600Mhz chips, it opened a new MOBO can of worms.
As an added cost you have to consider cooling. An older Thermaltake Frio Advanced runs about $50 and does a pretty good job with the 7850k, keeping it cool enough to get and extra .5 Ghz out of the cpu side and an extra 200+ Mhz out of the gpu side at the same time. Of course higher ram peed means hotter ram chips, so excelent case cooling or a ram cooler is advised. Water cooling is also a good option these days but it doesnt work well in all case designs. buy a compatible case or go with fans.
Your descrete GPU choice can come later when you get the 7850k, running at easily playable speeds on most games at 1080p on low settings. The ability to comunicate via pcie bus with newer R7 and R9 cards makes the choice an easy "how much do i want to spend?" for to price, the MSI R9 270X is a good choice, having an option for 2GB or 4GB, and clock speeds over 1Ghz. The GNC and Mantel features of the 7850k are also important to read into, as the support for mantle is increasing the framerates in most games, and GNC is to heart of why this chip is worth the money, allowing it to compute without overhead to do things with the CPU and GPU at the same time.
As for a MOBO, if you think you want to tweak your memory controler to allow for 2600Mhz Ram, you'll need a MOBO that can handle it off the bat. limits of 2133 and 2400 are common. If you don't want to worry about extreem ramspeeds, Gigabyte, Asus, ASRock, and MSI offer a few great MOBOs each in the FM2+ socket, Some of which do in fact support 2600Mhz ram.
Look for something you like that has the specs you need, read reviews, buy informed. Dont get caught in the AMD VS. Intel war. APUs are breaking new ground with kaveri. enjoy the enovation.