As per my understanding you are getting display while installing OS and booting, however, display disappears only while getting in to Desktop.
I suspect the resolution is the reason behind the issue. Your monitor is not supporting the resolution supported by your latest board and graphics card.
I suggest to try and perform the below mentioned steps:
1. Boot the system in safe mode and check whether you are able to work or not ?
( How to log in safe mode- Press F8 while booting , select safe mode ... )
2. Check with different monitor, preferably any latest monitor which can support higher resolution.