Increase Windows Page File

Increase the Windows Page File Size, I used to have the same issues but ignored the page file thing.

Go to Settings > System > About > Advanced System Settings (Under Related Settings)

You should see a window called "System Properties". Under the Advanced Tab, there should be a section for 'Performance'. Click Settings, and now another window called "Performance Options" should pop up. Under the Advanced Tab, there should be a section for 'Virtual Memory'. Press change.

(System Properties > Advanced > Perfonmance > Settings > Performance Options > Advanced > Virtual Memory > Change)

De-select the 'automatically manage paging file size for all drives'. Set the Minimum and Maximum amounts to the same thing. Set it to N GPUs * 8000. The reason is that it's set in MB, not GB. I set most of my rigs to 60000 MB to be safe.