Build Advice Dell T5500 Systems Upgrade

[attimoovy]

I have a Dell T5500 with the following specifications:

1. Dell 0D883f Motherboard
2. (x1) Xeon x5650 @2.67 GHz
3. 32 GB DDR3 RAM
4. Dell PSU @875 Watts
5. AMD R9 270 (GPU)
6. 100 GB SSD
7. WD Caviar Green (1TB, SATA-300, 32MB Buffer) | WD10EADS (HDD)

I want to completely convert this workstation to a complete (1080p @60FPS, AAA games) gaming rig. My main priorities are to upgrade the CPU, Motherboard, and GPU.
So far I have found these components to be interesting:
GPU: MSI Radeon RX 580
CPU: AMD RYZEN 3 3200G 4-Core @3.6 GHz (4.0GHz Max Bost)
Mobo: ASRock B450M PRO4 AM4 AMD Promontory B450 SATA 6Gb/s USB 3.1 HDMI Micro ATX AMD Motherboard
My budget is around $400 USD.
If anyone has any advice on any components I should upgrade, or if my chosen components would be compatible and/or would suffice, it would be greatly appreciated.

 

[kanewolf]

You are trying to save the cost of case and power supply by salvaging the Dell. I don't know how well that will work. The power supply is probably OK, but the case may not support a standard ATX motherboard. I wouldn't recommend reusing them. Too many possibilities for non-standard connectors.