Couple of things for you to do;
In your OP you say that the computer crashes so can you see if any crash dumps are available;
1. Copy any dmp files from C:\Windows\Minidump onto the desktop.
2. Select all of them, right-click on one, and click on Send To> New Compressed (zipped) Folder.
3. Upload the zip folder using the Attach button, bottom left of the dialogue input box
Download Speedfan and install it. Once it's installed, run the program and post here the information it shows. The information I want you to post is the stuff that is circled in the example picture I have attached.
If you are running on a vista machine, please go to where you installed the program and run the program as administrator.
(this is a screenshot from a vista machine)
Download then run HWMonitor and post a screenshot so that we have a comparison to the Speedfan results, details from here
To capture and post a screenshot;
Click on the ALT key + PRT SCR key..its on the top row..right hand side..now click on start...all programs...accessories...paint....left click in the white area ...press CTRL + V...click on file...click on save...save it to your desktop...name it something related to the screen your capturing... BE SURE TO SAVE IT AS A .JPG ...otherwise it may be to big to upload... then after typing in any response you have... click on browse...desktop...find the screenshot..select it and click on the upload button...then on the lower left...after it says upload successful...click on add reply like you normally would.
Screenshot instructions are provided to assist those that may read this topic but are not yet aware of the “how to”.
Download then run GPU-Z and attach screenshot/s of the results for us, GPU-Z from here