kernel-power 41 (63)

Hello, my first time posting here. Just want to say thanks beforehand and for reading my issue.
So I just built myself a computer the past month and it was running fine. Not until a few weeks later my computer would suddenly shutdown, i believe a hard hang, when i play games such as Warframe, Sniper Elite V2, or anything that might be demanding. Though when i just use my computer casually or whenever i render videos or compress videos my computer does not shutoff. So it might or might not be my cpu?
I went to check the event viewer and it listed kernel power id41 task 63. This event is exactly like scenario 3 from the windows support:
http://support.microsoft.com/kb/2028504#method3
I've looked around online and ive come down to the conclusion of cpu/thermal paste, faulty mobo or faulty psu? Could be other things too but I would like some help on this specific issue as it is really annoying me. Also, my case comes with 2 front intake fans and 1 exhaust fan in the back. I've added 2 more intake fans on the side and 2 more exhaust fans on top.

My system specs:
Windows 7 Ultimate 64bit
CPU: AMD FX 8320
MOBO: ASUS M5A99X EVO R2.0
GRAPHICS CARD: MSI NVIDIA GTX 750 TI 2GB OC Edition
RAM: G.Skill Ares Series (2x4GB)
PSU: LEPA MaxGold 500W 80+ Gold
CASE: Corsair Carbide Series Black 400R Mid Tower
SSD: PNY XLR8 120GB
HDD: TOSHIBA 1TB

My event viewer (recently has occurred more often.)
Log Name: System
Source: Microsoft-Windows-Kernel-Power
Date: 6/15/2014 2:22:21 AM
Event ID: 41
Task Category: (63)
Level: Critical
Keywords: (2)
User: SYSTEM
Computer: Damian-PC
Description:
The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Microsoft-Windows-Kernel-Power" Guid="{331C3B3A-2005-44C2-AC5E-77220C37D6B4}" ></Provider>
<EventID>41</EventID>
<Version>2</Version>
<Level>1</Level>
<Task>63</Task>
<Opcode>0</Opcode>
<Keywords>0x8000000000000002</Keywords>
<TimeCreated SystemTime="2014-06-15T09:22:21.526405300Z" ></TimeCreated>
<EventRecordID>21183</EventRecordID>
<Correlation ></Correlation>
<Execution ProcessID="4" ThreadID="8" ></Execution>
<Channel>System</Channel>
<Computer>Damian-PC</Computer>
<Security UserID="S-1-5-18" ></Security>
</System>
<EventData>
<Data Name="BugcheckCode">0</Data>
<Data Name="BugcheckParameter1">0x0</Data>
<Data Name="BugcheckParameter2">0x0</Data>
<Data Name="BugcheckParameter3">0x0</Data>
<Data Name="BugcheckParameter4">0x0</Data>
<Data Name="SleepInProgress">false</Data>
<Data Name="PowerButtonTimestamp">0</Data>
</EventData>
</Event>