BSOD (system_service_exception), freezes & crashes while gaming!

This has been happening ever since I bought my PC 2 years ago. I've taken it to 2 technicians several times who ran hardware tests and found nothing, thus weren't able to diagnose the problem. So a few weeks ago after I took it to the 2nd store I formatted my PC and BSODs alone have happened 2 times already. My PC crashes after multiple hours of gaming, either it freezes with colored bars on the screen or a blue screen happens (mostly the latter)

Temperatures are normal, video card drivers are up to date, passed all memory tests. Hardware seems to be fine. PLEASE HELP ME!

Specs:
OS: Windows 7 Ultimate 64-bit
Motherboard: ASUS M4A88T-M USB/3
CPU: AMD Phenom II x4 965 BE 3.4Ghz
RAM: 4GB
GPU: Asus Radeon HD 6850
PSU: Corsair CX-500W
HDD: Seagate Barracuda 500GB 7200rpm

Code:

Diagnostic Report (1.9.0027.0):
-----------------------------------------
Windows Validation Data-->

Validation Code: 0
Cached Online Validation Code: 0x0
Windows Product Key: *****-*****-Q6MMK-KYK6X-VKM6G
Windows Product Key Hash: 289NoAWl2ZoVfuieux/315WkDIc=
Windows Product ID: 00426-OEM-8992662-00173
Windows Product ID Type: 2
Windows License Type: OEM SLP
Windows OS version: 6.1.7601.2.00010100.1.0.001
ID: {534FDCEB-7A78-48B4-83B4-D036C5BEB568}(1)
Is Admin: Yes
TestCab: 0x0
LegitcheckControl ActiveX: N/A, hr = 0x80070002
Signed By: N/A, hr = 0x80070002
Product Name: Windows 7 Ultimate
Architecture: 0x00000009
Build lab: 7601.win7sp1_gdr.140303-2144
TTS Error: 
Validation Diagnostic: 
Resolution Status: N/A

Vista WgaER Data-->
ThreatID(s): N/A, hr = 0x80070002
Version: N/A, hr = 0x80070002

Windows XP Notifications Data-->
Cached Result: N/A, hr = 0x80070002
File Exists: No
Version: N/A, hr = 0x80070002
WgaTray.exe Signed By: N/A, hr = 0x80070002
WgaLogon.dll Signed By: N/A, hr = 0x80070002

OGA Notifications Data-->
Cached Result: N/A, hr = 0x80070002
Version: N/A, hr = 0x80070002
OGAExec.exe Signed By: N/A, hr = 0x80070002
OGAAddin.dll Signed By: N/A, hr = 0x80070002

OGA Data-->
Office Status: 109 N/A
OGA Version: N/A, 0x80070002
Signed By: N/A, hr = 0x80070002
Office Diagnostics: 025D1FF3-364-80041010_025D1FF3-229-80041010_025D1FF3-230-1_025D1FF3-517-80040154_025D1FF3-237-80040154_025D1FF3-238-2_025D1FF3-244-80070002_025D1FF3-258-3

Browser Data-->
Proxy settings: N/A
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Win32)
Default Browser: C:\Program Files (x86)\Google\Chrome\Application\chrome.exe
Download signed ActiveX controls: Prompt
Download unsigned ActiveX controls: Disabled
Run ActiveX controls and plug-ins: Allowed
Initialize and script ActiveX controls not marked as safe: Disabled
Allow scripting of Internet Explorer Webbrowser control: Disabled
Active scripting: Allowed
Script ActiveX controls marked as safe for scripting: Allowed

File Scan Data-->

Other data-->
Office Details: <GenuineResults><MachineData><UGUID>{534FDCEB-7A78-48B4-83B4-D036C5BEB568}</UGUID><Version>1.9.0027.0</Version><OS>6.1.7601.2.00010100.1.0.001</OS><Architecture>x64</Architecture><PKey>*****-*****-*****-*****-VKM6G</PKey><PID>00426-OEM-8992662-00173</PID><PIDType>2</PIDType><SID>S-1-5-21-1182795770-1792938603-1278253175</SID><SYSTEM><Manufacturer>System manufacturer</Manufacturer><Model>System Product Name</Model></SYSTEM><BIOS><Manufacturer>American Megatrends Inc.</Manufacturer><Version>0704   </Version><SMBIOSVersion major="2" minor="5"/><Date>20120106000000.000000+000</Date></BIOS><HWID>7AEE3C07018400FA</HWID><UserLCID>0816</UserLCID><SystemLCID>0816</SystemLCID><TimeZone>Hora padrão de GMT(GMT+00:00)</TimeZone><iJoin>0</iJoin><SBID><stat>3</stat><msppid></msppid><name></name><model></model></SBID><OEM><OEMID>_ASUS_</OEMID><OEMTableID>Notebook</OEMTableID></OEM><GANotification/></MachineData><Software><Office><Result>109</Result><Products/><Applications/></Office></Software></GenuineResults>  

Spsys.log Content: 0x80070002

Licensing Data-->
Versão do serviço de licenciamento de software: 6.1.7601.17514

Nome: Windows(R) 7, Ultimate edition
Descrição: Windows Operating System - Windows(R) 7, OEM_SLP channel
ID da Activação: 7cfd4696-69a9-4af7-af36-ff3d12b6b6c8
ID da Aplicação: 55c92734-d682-4d71-983e-d6ec3f16059f
PID Expandido: 00426-00178-926-600173-02-2070-7601.0000-1542014
ID da Instalação: 021512004212077460268151920594167433108761370313066260
URL de Certificado do Processador: http://go.microsoft.com/fwlink/?LinkID=88338
URL de Certificado do Computador: http://go.microsoft.com/fwlink/?LinkID=88339
URL da Licença de Utilização: http://go.microsoft.com/fwlink/?LinkID=88341
URL de Certificado da Chave do Produto: http://go.microsoft.com/fwlink/?LinkID=88340
Chave de Produto Parcial: VKM6G
Estado da Licença: Licenciado
Contagem de rearmamentos restantes do Windows: 3
Hora fidedigna: 13-06-2014 17:05:15

Windows Activation Technologies-->
HrOffline: 0x00000000
HrOnline: 0x00000000
HealthStatus: 0x0000000000000000
Event Time Stamp: 6:4:2014 13:52
ActiveX: Registered, Version: 7.1.7600.16395
Admin Service: Registered, Version: 7.1.7600.16395
HealthStatus Bitmask Output:


HWID Data-->
HWID Hash Current: NgAAAAEABAABAAEAAAADAAAAAgABAAEA6GFoduItXEE4mFT5EDNkZOKVYj3O7ovICkDMyI4u

OEM Activation 1.0 Data-->
N/A

OEM Activation 2.0 Data-->
BIOS valid for OA 2.0: yes
Windows marker version: 0x20001
OEMID and OEMTableID Consistent: yes
BIOS Information: 
  ACPI Table Name	OEMID Value	OEMTableID Value
  APIC			010612		APIC1412
  FACP			010612		FACP1412
  SRAT			AMD   		FAM_F_10
  HPET			010612		OEMHPET 
  MCFG			010612		OEMMCFG 
  OEMB			010612		OEMB1412
  SSDT			A M I 		POWERNOW
  SLIC			_ASUS_		Notebook

God damn you guys, a friend of mine installed it, I don't know if it's genuine or not. Just please help me out on this, I don't see how that could relate to the BSODs in the first place.