Please post the exact error messages you are receiving.
When the computer freezes does this happen no matter what your a doing, or does this occur when doing one thing only, like playing games?
Please download and install Speccy
to provide us with information about your computer. Clicking on this link will automatically initiate the download.
The one piece of information the Speccy will not provide is the make and model of your PSU. If you know what it is please post this along with the Speccy link which will be generated.
When Speccy opens you will see a screen similar to the one below.
Click on File which is outlined in red in the screen above, and then click on Publish Snapshot.
The following screen will appear, click on Yes.
The following screen will appear, click on Copy to Clipboard.
In your next post right click inside the Reply to Topic box, then click on Paste. This will load a link to the Speccy log.