for clearing everything up i will say i did searched the forum, did read similar problems and did all the steps that was suggested there.
* Asrock N68-S UCC
* AMD Athlon II X3 450
* DDR3 1333mhz 2x2gb ram
* MSI GTX 460 HAWK
* WD 500gb hard drive
* 650W PSU.
Operating system: Windows 7 Ultimate (64bit)
Problem: Computer gets locked up at random times and only solution for that is the reset button, nothing else works. After it gets boot up back again there is no error messages apart the ones that windows didnt shut down clearly etc..
Steps i did:
* I did checked, found problems on hard drive, replaced with new one and clean format and reinstall of the system completely. - Problem still there.
* Did run latest Memtest86+ (twice) to make sure that ram is ok, it showed no errors both times, however i did replaced it temporaly with known good ram sticks and run the system with it. - Problem still there.
* Reassambled all the system by cleaning every part of it from the dusts, reaplied new thermal paste to CPU. - Problem still there.
* Made some tests to verify that the system has enought power to run with and connected 480w PSU for a system only and the other one 650w to GPU only. Gues what? -Problem still there.
* So yesterday i made one more change to clear last parts from being wrong purchase and so ever. I did replaced GPU with ATI Radeon HD3870. So the clear boot without lock up from yesterday 2013/09/07 19:20. So far..
by the way. I did read about CUDA problems and sometimes it makes couse the windows think that driver stops responding and reloads the VGA driver. I made the registry hack to prevent that and that solved the problem that was. But after reformat it didnt came up again so i decided to not apply the same registry hack to make the response time for GPU bigger.
Im willing to read and try any suggestions, maybe someone with same hardware run in to simillar problems and wants to share how they solved it.
thank you for your responces.