Okay to truely MAX 4k @ 60fps you need twin GTX 980 Tis.
This puts you a bit over budget
PCPartPicker part list / Price breakdown by merchant
| Type | Item | Price |
|---|---|---|
| CPU | Intel Core i5-4690K 3.5GHz Quad-Core Processor | $308.50 @ shopRBC |
| CPU Cooler | Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler | $37.05 @ Vuugo |
| Motherboard | Asus Z87-Pro ATX LGA1150 Motherboard | $148.55 @ DirectCanada |
| Memory | Kingston 8GB (2 x 4GB) DDR3-1333 Memory | $52.74 @ DirectCanada |
| Storage | Samsung 850 EVO-Series 250GB 2.5" Solid State Drive | $108.05 @ Vuugo |
| Storage | Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive | $63.05 @ Vuugo |
| Video Card | MSI GeForce GTX 980 Ti 6GB Video Card (2-Way SLI) | $829.98 @ NCIX |
| Video Card | MSI GeForce GTX 980 Ti 6GB Video Card (2-Way SLI) | $829.98 @ NCIX |
| Case | NZXT Source 220 ATX Mid Tower Case | $69.99 @ Newegg Canada |
| Power Supply | EVGA 1000W 80+ Gold Certified Fully-Modular ATX Power Supply | $165.37 @ DirectCanada |
| Operating System | Microsoft Windows 10 Home OEM (64-bit) | $123.00 @ shopRBC |
| Prices include shipping, taxes, rebates, and discounts | ||
| Total (before mail-in rebates) | $2776.26 | |
| Mail-in rebates | -$40.00 | |
| Total | $2736.26 | |
| Generated by PCPartPicker 2016-01-08 14:22 EST-0500 |
Now if you dropped down to medium settings for some AAA titles you can run 60 FPS, some games Ultra with no AA (but at 4k you shouldn't REALLY need it)
You could go with 1 980 Ti
PCPartPicker part list / Price breakdown by merchant