Computer shuts down without any warning

System Specs:

• OS: Windows 10 Home Single Language 64 bits (10.0, Build 10240)
• System Manufacturer: ECS
• System Model: A970M-A DELUXE
• Mother Board: Biostar A8553
• Processor: AMD FX(tm)-8120 Eight-Core Processor (8 CPUs), ~3.1GHz
• Memory: 6144MB RAM
• Page File: 1512MB used, 3950MB available
• Direct X version: 11.2
• GPU: NVIDIA GeForce GTX 550 Ti
• Power Supply: Aiteg DLP-21A (ATX 550W P4)

My computer is used mostly for working on software like Pro Tools, Quark Xpress, Photoshop, and video games. Usually, it shuts down when running software that needs more power to run (Pro Tools and games mostly). Sometimes it can run these programs for a while, but some games, especially Skyrim, makes it shut down as soon as it loads. There is no warning, the CPU simply shuts down as if there was a power outage.

The issue has been happening for a while now and I haven't been successful at pinpointing the cause of the problem.

The first time my machine started having issues was when I replaced my old Motherboard/Processor with the new AMD Processor. The power supply it had at the time started smelling like burnt plastic and let out a bit of smoke, I replaced it as soon as I could with another power supply, which one day I simply didn't let me power on my computer. Finally, I replaced it again with the current power supply, which the store I took it to assured me it would work without any issues. I've formatted the computer before I updated from Windows 8 to 10 so its a fresh install.

My best guess is that the power supply they sold me is the issue and it shuts down to prevent any damage to the machine. I also read that AMD processors and NVIDIA GPUs have compatibility issues, which makes me wonder if the issue is there.

Bottom line is I'd like to know exactly what causes the problem so I can address it and fix it. Any help is very appreciated. Cheers.