All Steam games completely freezing my PC

Hi there, I'm new to this kind of thing, so sorry if I put this in the wrong area. Okay, so the problem I've been having is after after an hour or so of playing any steam games(It happens faster on Source Games like Gmod, cs go etc.) My PC will completely freeze, and the sound starts to loop and I can't move my mouse, open task manager or even turn off my computer with the power button, I need to pull out the power plug. This may have been caused by a steam update around two weeks ago, I know that probably won't help but whatever.

Thanks alot -
Zeke

PC Specs:

Processor(s)
•Processor
◦CPU_Name: Intel(R) Core(TM) i5-3330 CPU @ 3.00GHz
◦CPU_Manufacturer: GenuineIntel
◦CPU_Caption: Intel64 Family 6 Model 58 Stepping 9
◦CPU_Version:
◦CPU_ProcessorId: BFEBFBFF000306A9
◦CPU_CurrentClockSpeed: 1590MHz
◦CPU_AddressWidth: 64Bits
◦CPU_DataWidth: 64Bits
◦CPU_SocketDesignation: CPU 1
•Verified Hardware Device against Order: VARIABLEXYZ
•Verify Correct Processor Frequency

System Memory

BIOS Information
•BIOS_Manufacturer: Alienware
•BIOS_Name: BIOS Date: 08/16/12 10:01:16 Ver: 04.06.05
•BIOS_Version1: A08
•BIOS_Version2: ALWARE - 1072009

Motherboard Information
•MB_Manufacturer: Alienware
•MB_Product: 06G6JW
•MB_SerialNumber: ..CN697022A82389.
•MB_Version: A00

Video Adapter
•Video_Caption: NVIDIA GeForce GT 640
•Video_AdapterRAM: 1024MB
•Video_DriverVersion: 8.17.12.9636

Hard Drive(s)
•WDC WD10EZEX-75ZF5A0 ATA Device
◦Disk_Model: WDC WD10EZEX-75ZF5A0 ATA Device
◦Disk_Size: 1000 GB
◦Disk_Partitions: 4
◦Disk_TotalHeads: 255
◦Disk_TotalCylinders: 121601
◦Disk_TotalTracks: 31008255
◦Disk_TracksPerCylinder: 255

Optical Drives / Other Storage
•PLDS DVD+-RW DL-8A4SH ATA Device

OperatingSystem: MS Windows 7 Home Premium Edition

DirectXVersion: DirectX 11

IRQ Configuration
• 0 System timer
• 1 -empty-
• 2 -empty-
• 3 -empty-
• 4 Intel(R) 6 Series/C200 Series Chipset Family SMBus Controller - 1C22
• 5 -empty-
• 6 -empty-
• 7 -empty-
• 8 System CMOS/real time clock
• 9 -empty-
• 10 -empty-
• 11 -empty-
• 12 -empty-
• 13 Numeric data processor
• 14 -empty-
• 15 -empty-
• 16 NVIDIA GeForce GT 640
• 16 Intel(R) 6 Series/C200 Series Chipset Family USB Enhanced Host Controller - 1C2D
• 17 High Definition Audio Controller
• 17 Intel(R) 6 Series/C200 Series Chipset Family PCI Express Root Port 2 - 1C12
• 18 Dell Wireless 1506 802.11b/g/n (2.4GHz)
• 19 Intel(R) 6 Series/C200 Series Chipset Family 6 Port SATA AHCI Controller - 1C02
• 22 Intel(R) High Definition Audio - 1C20
• 23 Intel(R) 6 Series/C200 Series Chipset Family USB Enhanced Host Controller - 1C26
•190 Microsoft ACPI-Compliant System

Miscellaneous

Final Checks

Installed Devices Drivers
•Intel(R) 6 Series/C200 Series Chipset Family 6 Port SATA AHCI Controller - 1C02, 9-10-2010, 9.2.0.1011
•Microsoft Streaming Service Proxy, 6-21-2006, 6.1.7600.16385
•NVIDIA GeForce GT 640 , 3-22-2012, 8.17.12.9636
•NVIDIA High Definition Audio, 3-22-2012, 1.3.14.1
•Realtek PCIe GBE Family Controller, 6-10-2011, 7.46.610.2011
•ATA Channel 0, 6-21-2006, 6.1.7601.17514
•Intel(R) Core(TM) i5-3330 CPU @ 3.00GHz, 6-21-2006, 6.1.7600.16385
•ATA Channel 1, 6-21-2006, 6.1.7601.17514
•Realtek High Definition Audio, 11-2-2011, 6.0.1.6494
•Microsoft Streaming Tee/Sink-to-Sink Converter, 6-21-2006, 6.1.7600.16385
•Dell Wireless 1506 802.11b/g/n (2.4GHz), 11-22-2011, 9.2.0.469
•Generic volume shadow copy, 6-21-2006, 6.1.7600.16385
•Intel(R) Display Audio, 12-6-2011, 6.14.0.3090
•Intel(R) Core(TM) i5-3330 CPU @ 3.00GHz, 6-21-2006, 6.1.7600.16385
•Microsoft Streaming Tee/Sink-to-Sink Converter, 6-21-2006, 6.1.7600.16385
•Generic volume shadow copy, 6-21-2006, 6.1.7600.16385
•Generic volume shadow copy, 6-21-2006, 6.1.7600.16385
•PLDS DVD+-RW DL-8A4SH ATA Device, 6-21-2006, 6.1.7601.17514
•Intel(R) Core(TM) i5-3330 CPU @ 3.00GHz, 6-21-2006, 6.1.7600.16385
•Generic volume shadow copy, 6-21-2006, 6.1.7600.16385
•WDC WD10EZEX-75ZF5A0 ATA Device, 6-21-2006, 6.1.7600.16385
•Generic volume shadow copy, 6-21-2006, 6.1.7600.16385
•Intel(R) HD Graphics, 3-19-2012, 8.15.10.2696
•Intel(R) Core(TM) i5-3330 CPU @ 3.00GHz, 6-21-2006, 6.1.7600.16385
•Generic volume shadow copy, 6-21-2006, 6.1.7600.16385