Z68X UD3 B3 PC Crashing

[Mikk]

Hi there gigabyte forums!
So i have this problem that my PC crashes once in a while with complete freeze and sound looping :/ Windows event viewer say's this :

Log Name:      System
Source:        Microsoft-Windows-Kernel-Power
Date:          15.09.2012 0:30:43
Event ID:      41
Task Category: (63)
Level:         Critical
Keywords:      (2)
User:          SYSTEM
Computer:      mikk-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="2012-09-14T21:30:43.477624500Z" />
    <EventRecordID>153188</EventRecordID>
    <Correlation />
    <Execution ProcessID="4" ThreadID="8" />
    <Channel>System</Channel>
    <Computer>mikk-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>

My PC Specs:
Z68x UD3 B3 F12 Bios
I5 2500k 3.3ghz
Ati 6950 1gb
8GB Kingston 1333 mhz ram (name is too long so il put a link to the ram here http://www.newegg.com/Product/Product.aspx?Item=N82E16820134812 )
SAMSUNG HD103SJ
620W Seasonic

I have tryed everything reinstalling windows, switching RAM slots, updating drivers, memtest etc but still on luck :/ so im hoping you guys can help me

[spikey_richie]

You need to go and hunt down your Minidump file(s), and crack these open with the Microsoft minidump viewer tool. This will give you a lot more info than the event log.

[Mikk]

ok so my friend recommended doing HD tool test and this is the result http://www.upload.ee/image/2676848/15-september-2012_17-04.png and he told me that that HD is faulty but today my PC crashed like this. Monitor went completely black and in about 10 seconds the sound loop came back so is it video card problem, HD problem or maybe motherboards problem? please help...