Peripherals Shut Down with computer still on.

So I ran virus scans I doubt this is the problem, but the monitor goes black in a middle of a game most the time when playing leauge or hearthstone. Sometimes when browsing I think one time while doing nothing. Usually happens anywhere from 1 to 5 hours and happens frequently 3-4 times a day, some days once or twice.
Monitor goes black I sometimes hear a loud buzzing sound through my headphones that seems to go on for a long time. The fans are still on and I'm force to reboot and I end up starting up the computer back up in normal mode.
Not sure how to pinpoint the problem or where to find logs of what happened prior to the monitor going black.
My guess is either graphics card, power supply or motherboard. I'm willing to check components and see if any pieces are rusted or damaged. I could use on tips on what parts to look at and what to look for.
But yeah helping me first find out what the problem is first seems whats best.

CPU: AMD Phenom(tm) II X6 1100T Processor
Mobo: MSI 870A-G54 (MS-7599)
BIOS: Default System BIOS
Total Memory: 14.00 GB Usable: 14.00 GB

HDD: (1) Hitachi HDS721010CLA332 ATA Device (2) WDC WD5000AAKX-001CA0 ATA Device (3) WDC WD5000AVVS-63H0B1 ATA Device (4) IC USB Storage-CFC USB Device (5) IC USB Storage-MMC USB Device (6) IC USB Storage-MSC USB Device (7) IC USB Storage-SMC USB Device

Sound Card: (1) NVIDIA High Definition Audio (2) HD Webcam C310 (3) NVIDIA High Definition Audio (4) NVIDIA Virtual Audio Device (Wave Extensible) (WDM) (5) Realtek High Definition Audio (6) NVIDIA High Definition Audio (7) NVIDIA High Definition Audio

Graphics Card: NVIDIA GeForce 210

OS: Microsoft Windows 7 Home Premium 64-bit 7601 Multiprocessor Free Service Pack 1

Power Supply: Antec BP500U ATX12V Power Supply, 500 W

Security program kapersky pure 3.0, I don't think I have any cleanup or registry programs on at the moment.

No unexpected shutdowns today, yet yesterday it happened 3-4 times and the day before that too. I have not played any leauge today, but I did play a lot of hearthstone which I did have some shutdowns while playing in yesterday.
It seems to be random but happens to be when playing my games and usually later when im winning.
There has been some ddos attacks on riot and blizzard this past week.

I checked the days when I had the crashes and checked the logs nearest to when it said the system shutdown unexpected.
I found that before each of them had these.
The Application Experience service entered the stopped state.
The WinHTTP Web Proxy Auto-Discovery Service service entered the stopped state.
The Software Protection service entered the stopped state.
The Windows Installer service entered the stopped state.
The Windows Error Reporting Service service entered the stopped state.
Something like this with these entering running and stop states. Some appear before the crashes and others do not, thought I might bring this up. Also these were not listed as errors,critical or warnings only the unexpected shutdowns were listed as an error then after 4-5 logs following after there is always a critical log saying.
The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.
Source Kernal-Power, not sure if any this can assist but I will keep looking and will try to use Who Crashed the next time I have to reboot.

Sorry about not replying but the problem seemed to go away for a few weeks and came back just now. I'll look into finding my ram and their slots.
Here is a a warning I found in event viewer around the time when I had to shutdown.