So, we did a few 4K builds in the past, but after looking at some benchmarks from competitors, crunching some numbers, we found a way to get 4K for $400 less than the last major 4K build at great frame rates. As usual, all prices are USD and from Amazon unless otherwise stated. Let's get started.
CPU: Intel Core i5-4690k
Similar to the last 4K build, we're going with the i5-4690k. It's a really good chip, and won't bottleneck your GPUs in most, if not all games. Go on almost any PC board and ask what CPU you should get for gaming, this will be yelled from the mountain tops. It overclocks well, and doesn't get hot at stock where it performs well anyway.
CPU Cooler: Corsair H60
The Corsair H60 is a single fan all-in-one water cooling setup, which is fine for this CPU. If you don't plan on pushing your CPU a ton, this will be perfect, and will help keep the inside of your case clean. It can accept a decent overclock, though, but the temps will be higher than a few other options.
Motherboard: MSI Z97S SLI Krait Edition
This motherboard is pretty nice for the money. It's a Z97 board for $100 and offers stuff that the more expensive motherboards offer as well. SLI/Crossfire support, USB3.0 for the front with four ports in the back, a really nice color scheme if you care about that, and heat sinks on the MOSFETs and capacitors. You'll be totally fine with this motherboard, which don't make a huge difference in gaming anyway.
So this RAM is kind of slow, yes, but for $100 for 16GB, you can't complain about speed too much. This is a great deal for one, and it's plenty of RAM for any system. If you want less, you definitely could go with 8GB and put the other money into the CPU cooler or something. G.Skill makes good RAM in my opinion, so for $100 USD at Newegg at time of writing, this will do fine.
SSD: Crucial MX100 256GB
So within this budget, you can do a 256GB SSD. This is tons of space for popular games and apps, and is great for booting. The Crucial MX100 is pretty fast too, with 550MB/sec reads, and 330MB/sec writes, you'll be doing great with this SSD. If you want something smaller, or no SSD at all, that's fine too, but this is a great SSD for the money.
So just like the Seagate Barracuda we usually have, but triple the capacity. This will help store everything you could want, unless you wanna put the next 4 copies of Call of Duty, cause they're huge. Perfectly capable HDD, SATA 3, everything wonderful. And less than $100 right now.
According to most benchmarks, the R9 290X is as good if not better than the GTX 970 when it comes to 4K. With the fluctuation of the GTX 970 prices, it might be safer to go with the R9 290X, and no one knows AMD cards better than Sapphire. The Tri-X cooler is insanely good, really big, and keeps even the hottest Hawaii chips cool. Triple fan design, two and a half slot card, and a beefy heatsink - you will be able to overclock this and keep it cool under load, even at 4K.
Case: Phanteks Enthoo Pro
If anyone is familiar with the Hardware Canucks on YouTube, you'll know they really like Phanteks. And it's pretty easy to see why. Roomy, great air flow, great construction, everything you need for your hardware, and easy to use. It also looks pretty snazzy if you ask me.
The RM850 is a really good power supply from Corsair. Fully modular, 80+ Gold, so you can customize it and get clean power running to all your hardware easily. No need to mess around with cable management either. Just use what you need. It also looks snazzy, but who looks at power supplies and thinks that? (I do.)
So, there we have it. If you shop around, use rebates and promos, you could get this setup for $1218.02, almost $400 less than the other setup. This rig will run any game at glorious frame rates at sub 4K, and will make your games look amazing at 4K while still running at acceptable frame rates. If you're a graphics snob, you will be pleased with this build for certain.
Be sure to check out TechRaptor's Gamefanshop, and if you wanna keep seeing builds like this or have any suggestions, post a comment.