FPS drop/Computer crash/Start it self with Blackscreen

[Kaladin Storm]

Having this problem for years and its so ****ing anoying.
every time and every game I play after 40 min this **** happends.

Ram 12, GB
64 bits
i7
Windows 8
Geforce GT 640

and the game I play is LoL at the lowest ****ing settings that is possible

 

[Kaladin Storm]

Also my background whe I start just get black but everything still works at that moment

 

[mailpup]

Kaladin Storm, please watch your swearing. Thanks.

 

[Cycloid Torus]

What could cause..."schlepping computer"?

Heat throttling due to dust blanket inside - clean inside of computer (see Youtube videos)

Heat throttling due to hardened thermal paste on CPU or GPU or southbridge - clean & replace (see Youtube for videos on this)

Virus / trojan / rootkit - run several scans and if any 'surprises', pursue in Virus Removal topic in next forum

Failing PSU - check voltage and temps against norms +/-3% or so on 12v and 5v rails using HWInfo (hwinfo.com)

Failing HDD - check SMART, run cleanup/defrag, replace

Drivers: need updated drivers to make your system work well with Win8 (hope its 8.1) - check motherboard manufacturer's site

You can post about your progress through the list and there might be more helpful ideas