BSOD mostly when playing games. but can happend whenever

okay so i wrote a nice post and was tweaking to make it neat.. the comp crashed.. now for the speed version.

latest whocrashed dump file

On Mon 12-11-2012 21:25:32 GMT your computer crashed
crash dump file: C:\Windows\Minidump\111212-14367-01.dmp
This was probably caused by the following module: ntoskrnl.exe (nt+0x4A50AC)
Bugcheck code: 0x124 (0x0, 0xFFFFFA8004FD34F8, 0x0, 0x0)
Error: WHEA_UNCORRECTABLE_ERROR
file path: C:\Windows\system32\ntoskrnl.exe
product: Microsoft® Windows® Operating System
company: Microsoft Corporation
description: NT Kernel & System
Bug check description: This bug check indicates that a fatal hardware error has occurred. This bug check uses the error data that is provided by the Windows Hardware Error Architecture (WHEA).
This is likely to be caused by a hardware problem problem. This problem might be caused by a thermal issue.
The crash took place in the Windows kernel. Possibly this problem is caused by another driver that cannot be identified at this time.

Story and clarification:
bought a second hand comp 4 days ago, had a fresh install of windows 7 64x started to install updates and programs, tried running civ 5 for the first time, gave me 10 min and crashed, since then it crashes sometimes every 10 min and sometimes up to 4 hours or so. seems to happend if i do alot at once, like closing alot of windows, refreshing browser and so on, or in a game, it will never crash when completly idle. but something as small as moving the mouse can make it crash. have tried everything i can think of. i dont know how to look at a dump file. please help

specs can be seen in my profile (sorry)

what iwe done

* Clean install, all drives updated afterwards i have even tried downgrading the nvidia driver.
* checked voltage and heating with speedfan (have tried having open windows and added an extra fan. making the higest value 42C on the cpu, everything else is below 30)
* installed all drivers (even tried downgrading graphixs driver
* memtest (clean), windows 7 mem test (clean)
* cpu test (Prime 95)
* dissasembled comp and put back together
* replaced graphix card and power supply
might have overlooked something


the comp is not OC in any way

i am willing to do anything.

Welcome aboard.

Code:

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*                                                                             *
*                        Bugcheck Analysis                                    *
*                                                                             *
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Use !analyze -v to get detailed debugging information.

BugCheck 124, {0, fffffa8004f25038, 0, 0}

Probably caused by : GenuineIntel

Followup: MachineOwner
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It is a hardware related crash. Follow Stop 0x124 - what it means and what to try.