Why does my computer keep freezing?

My computer freezes completely which means I have to restart it.
I Use the stock CPU cooler. But is that the reason it freezes?
I have 8GB RAM.
And no I have not yet run the stress test.

What does memtest do?

I've used it and there doesnt seem to be a problem. i also updated the bios and tried playing bioshock infinite and after 20 mins it crashed.

no its 8gb, but it hasn't solved my problem And my PC wont let me play games as it keeps on freezing, oh and also my CPU it very loud, even when I'm not playing games. I'm starting to worry. Thanks for helping me.
P.S, will buying a new heat-sink and fan solve my problem as my fan did not make as much noise before i brought my new motherboard and power supply.

Ok I have downloaded a program called WhoCrashed and it is all related to a driver issue called atikmdag.sys i have tried to re install the amd catalyst suite, but the freesing problem still occurs and Who Crashed says:

Crash dump directory: C:\Windows\Minidump

Crash dumps are enabled on your computer.

On Thu 27/02/2014 17:11:10 GMT your computer crashed
crash dump file: C:\Windows\Minidump\022714-35849-01.dmp
This was probably caused by the following module: atikmdag.sys (atikmdag+0x277CE)
Bugcheck code: 0xA0000001 (0x5, 0x0, 0x0, 0x0)
Error: CUSTOM_ERROR
file path: C:\Windows\system32\drivers\atikmdag.sys
product: ATI Radeon Family
company: Advanced Micro Devices, Inc.
description: ATI Radeon Kernel Mode Driver
A third party driver was identified as the probable root cause of this system error. It is suggested you look for an update for the following driver: atikmdag.sys (ATI Radeon Kernel Mode Driver, Advanced Micro Devices, Inc.).
Google query: Advanced Micro Devices, Inc. CUSTOM_ERROR



On Thu 27/02/2014 17:11:10 GMT your computer crashed
crash dump file: C:\Windows\memory.dmp
This was probably caused by the following module: atikmdag.sys (atikmdag+0x277CE)
Bugcheck code: 0xA0000001 (0x5, 0x0, 0x0, 0x0)
Error: CUSTOM_ERROR
file path: C:\Windows\system32\drivers\atikmdag.sys
product: ATI Radeon Family
company: Advanced Micro Devices, Inc.
description: ATI Radeon Kernel Mode Driver
A third party driver was identified as the probable root cause of this system error. It is suggested you look for an update for the following driver: atikmdag.sys (ATI Radeon Kernel Mode Driver, Advanced Micro Devices, Inc.).
Google query: Advanced Micro Devices, Inc. CUSTOM_ERROR



On Fri 21/02/2014 15:33:14 GMT your computer crashed
crash dump file: C:\Windows\Minidump\022114-34351-01.dmp
This was probably caused by the following module: atikmdag.sys (atikmdag+0x277CE)
Bugcheck code: 0xA0000001 (0x5, 0x0, 0x0, 0x0)
Error: CUSTOM_ERROR
file path: C:\Windows\system32\drivers\atikmdag.sys
product: ATI Radeon Family
company: Advanced Micro Devices, Inc.
description: ATI Radeon Kernel Mode Driver
A third party driver was identified as the probable root cause of this system error. It is suggested you look for an update for the following driver: atikmdag.sys (ATI Radeon Kernel Mode Driver, Advanced Micro Devices, Inc.).
Google query: Advanced Micro Devices, Inc. CUSTOM_ERROR



On Fri 14/02/2014 18:47:34 GMT your computer crashed
crash dump file: C:\Windows\Minidump\021414-26410-01.dmp
This was probably caused by the following module: ntoskrnl.exe (nt+0x75BC0)
Bugcheck code: 0x1E (0xFFFFFFFFC0000005, 0xFFFFF88002F91B60, 0x0, 0x0)
Error: KMODE_EXCEPTION_NOT_HANDLED
file path: C:\Windows\system32\ntoskrnl.exe
product: Microsoft® Windows® Operating System
company: Microsoft Corporation
description: NT Kernel & System
Bug check description: This indicates that a kernel-mode program generated an exception which the error handler did not catch.
This appears to be a typical software driver bug and is not likely to be caused by a hardware problem.
The crash took place in the Windows kernel. Possibly this problem is caused by another driver that cannot be identified at this time.

i have opened the side panel and it hasn't turned off since i have played bioshock infinite and sleeping dogs for 5 hours.