This build is a bit overkill for your purpose, but it allows you to switch to bigger games without problem and keeps your pc will still be decent next year.
PCPartPicker part list / Price breakdown by merchant
| Type | Item | Price |
|---|---|---|
| CPU | Intel Core i5-6500 3.2GHz Quad-Core Processor | $194.99 @ SuperBiiz |
| Motherboard | Gigabyte GA-H110M-A Micro ATX LGA1151 Motherboard | $53.99 @ SuperBiiz |
| Memory | G.Skill NT Series 8GB (1 x 8GB) DDR4-2133 Memory | $29.98 @ Newegg |
| Storage | PNY CS1311 240GB 2.5" Solid State Drive | $59.99 @ Amazon |
| Storage | Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive | $46.98 @ OutletPC |
| Video Card | EVGA GeForce GTX 950 2GB Superclocked+ ACX 2.0 Video Card | $119.99 @ Newegg |
| Case | Corsair Carbide Series 88R MicroATX Mid Tower Case | $37.99 @ Micro Center |
| Power Supply | Corsair CX 430W 80+ Bronze Certified Semi-Modular ATX Power Supply | $27.98 @ Newegg |
| Operating System | Microsoft Windows 10 Home OEM (64-bit) | $83.89 @ OutletPC |
| Prices include shipping, taxes, rebates, and discounts | ||
| Total (before mail-in rebates) | $710.78 | |
| Mail-in rebates | -$55.00 | |
| Total | $655.78 | |
| Generated by PCPartPicker 2016-05-13 18:47 EDT-0400 |
Poweful quad core processor for streaming and won't have trouble with any games.
Basic motherboard which works fine if you don't need any special features.
Plenty of memory for now and can add another 8Gb in future.
Good budget solid state drive for faster boot and loads. Plenty of hard drive space if you need for other games and files.
Good budget GPU that can easily handle Overwatch easily and can also play most AAA games on high settings. You can get R9 380 or GTX 960 for less than 200$ if you wish to play almost any game on max settings.
Good quality small case. You can check the size here to see if it's small enough for you.
Decent quality modular budget PSU.
Since you don't really need 1Tb of hard drive space for your minimum goal, here's a cheaper build that will be fine for you, but gets outdated faster and will have some trouble if you wish to switch to bigger games:
PCPartPicker part list / Price breakdown by merchant
| Type | Item | Price |
|---|---|---|
| CPU | Intel Core i3-6100 3.7GHz Dual-Core Processor | $110.99 @ SuperBiiz |
| Motherboard | Gigabyte GA-H110M-A Micro ATX LGA1151 Motherboard | $53.99 @ SuperBiiz |
| Memory | G.Skill NT Series 8GB (1 x 8GB) DDR4-2133 Memory | $29.98 @ Newegg |
| Storage | PNY CS1311 240GB 2.5" Solid State Drive | $59.99 @ Amazon |
| Video Card | EVGA GeForce GTX 750 Ti 2GB Superclocked Video Card | $106.98 @ Newegg |
| Case | Corsair Carbide Series 88R MicroATX Mid Tower Case | $37.99 @ Micro Center |
| Power Supply | Corsair CX 430W 80+ Bronze Certified Semi-Modular ATX Power Supply | $27.98 @ Newegg |
| Operating System | Microsoft Windows 10 Home OEM (64-bit) | $83.89 @ OutletPC |
| Prices include shipping, taxes, rebates, and discounts | ||
| Total (before mail-in rebates) | $571.79 | |
| Mail-in rebates | -$60.00 | |
| Total | $511.79 | |
| Generated by PCPartPicker 2016-05-13 18:58 EDT-0400 |
Switched to weaker duo core CPU. It should work fine for streaming Overwatch.
Dropped the HDD since you don't need it just for overwatch and there's still room on SSD if you only install a game or two.
Cheaper GPU that should handle Overwatch on max just fine, but new games might give it trouble.