looking for a gaming pc that can run LoL,Csgo and microsoft 365 smoothly for 4-5years.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Pentium G4560 3.5GHz Dual-Core Processor ($59.99 @ SuperBiiz)
Motherboard: MSI B250M PRO-VDH Micro ATX LGA1151 Motherboard ($69.49 @ SuperBiiz)
Memory: ADATA XPG Z1 8GB (2 x 4GB) DDR4-2800 Memory ($54.89 @ OutletPC)
Storage: Crucial MX300 275GB M.2-2280 Solid State Drive ($89.88 @ OutletPC)
Video Card: EVGA GeForce GTX 1050 Ti 4GB SC GAMING ACX 2.0 Video Card ($139.99 @ Amazon)
Case: Fractal Design Core 1000 USB 3.0 MicroATX Mid Tower Case ($39.99 @ NCIX US)
Power Supply: SeaSonic 520W 80+ Bronze Certified Fully-Modular ATX Power Supply ($53.99 @ SuperBiiz)
Operating System: Microsoft Windows 10 Home OEM 64-bit ($88.58 @ OutletPC)
Total: $596.80
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-04-09 11:48 EDT-0400

^ This build has an entry level CPU that you'll probably want to replace at some point, but the motherboard will accept up to a Core i7 7700 if you find the Pentium is getting a bit weak. It has 2 extra RAM slots, and a reliable power supply that is more than adequate for anything you could put in it. If you wanted a slightly stronger machine from the start, you might choose to go with an i7 7500 instead (+$140) and a Radeon RX470 (+$40) or even a GTX 1060 (+$100ish).

If you wanted to go with a small form factor system, you could instead use this motherboard, case and power supply for a PC that's just as fast and has onboard WiFi, but takes up 1/3 the space:

https://www.newegg.com/Product/Product.aspx?Item=9SIA2F859N7309&cm_re=b250_itx-_-13-130-999-_-Product

https://www.newegg.com/Product/Product.aspx?Item=N82E16811352058

https://www.newegg.com/Product/Product.aspx?Item=N82E16817256176
 
Solution