I upgraded from an 8-year old PC. This is a HUGE upgrade for me. The old PC is becoming a home server.
Old PC: MSI P35 Platinum LGA 775 Motherboard / Intel Core 2 Quad Q9650 / PNY GeForce GTS 250 / 6GB of slow DDR2 RAM
I was originally planning an AMD FX-8320 build to keep this system as cheap as possible. I saw a sweet deal for a free motherboard (!) with purchase of an i5-6600K on B+H so I changed up my plans. I ended up with an i5-6600K for about $20 more than the FX-8320.
My main concern here was performance in Adobe Lightroom and Photoshop. I'm a hobby photographer and those programs DRAGGED on my old PC. I stopped posting online because of how long it took to develop RAW images. I focused on quad-core/octo-core chips because Adobe's newer CC software threads pretty well. Performance benefits are pretty flat after 4 cores but it helps with exporting.
Gaming was a secondary concern. I couldn't justify spending another $200 on the R9 390. I love gaming but I don't play enough to invest that money. I might upgrade the video card later this year but so far, the R9 380 has been fantastic. Everything's run perfectly so far.
I got some other great deals -- Best Buy pricematched Newegg on the SSD at $59.99, I used a $10 gift card and a 10% off coupon. $20 rebate on the R9 380, $15 rebate on the EVGA 600W PSU.
I purchased Windows 7 Pro from my campus bookstore for $20 and used a free upgrade to the Windows 10 Education edition. So I was able to get Win10 for $20.