Hello.

My PC randomly reboots, mostly when gaming. Maybe twice in a day and even more when gaming. At first I thought it's overheating, but then PC started rebooting when watching movie or browsing net. I checked CPU temps in SpeedFan app it show that it's 60-80C while I am browsing net. I tried other app it's called Speccy it shows that CPU is 40-50C while browsing. I'll try to describe how my PC reboots: Monitor turns off and strange sound happens it's like RRRRRRRRRRRRRRRRRRRRR but my PC still running until I hold the power button, but not everytime I need to hold power button.

I looked into even viewer and that's what I see:

Code:
The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.

Critical	2014.08.01 23:30:19	Kernel-Power	41	(63)


Log Name:      System
Source:        Microsoft-Windows-Kernel-Power
Date:          2014.08.01 23:30:19
Event ID:      41
Task Category: (63)
Level:         Critical
Keywords:      (2)
User:          SYSTEM
Computer:      POVILAS-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}" />
    <EventID>41</EventID>
    <Version>2</Version>
    <Level>1</Level>
    <Task>63</Task>
    <Opcode>0</Opcode>
    <Keywords>0x8000000000000002</Keywords>
    <TimeCreated SystemTime="2014-08-01T20:30:19.010006200Z" />
    <EventRecordID>70184</EventRecordID>
    <Correlation />
    <Execution ProcessID="4" ThreadID="8" />
    <Channel>System</Channel>
    <Computer>POVILAS-PC</Computer>
    <Security UserID="S-1-5-18" />
  </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>
PC Specs:

Video card: GeForce GTX 560
CPU: i7-2600K @ 3.40GHz
Memory: 8192MB RAM
Sounds: Realtek High Defintion Audio
SSD Disk: Kingston 64GB


What I already did:
Changed PSU to CoolerMasters V550S
Did MemTest, GPU stress test, and some more things.



P.S Sorry for my english it's not my native language and If u need more information ask me. I have no idea where's the problem :(