Always best to give full PC specs, PSU. Motherboard, what monitors etc
A lot of times those can have a big impact on the issue.. eg a lot current gen issues have been around people using to weak a power supply.
My first thought here would be to the dvi adapter.
But have you checked/tried
- If windows is picking them up at all, ie go to detect monitor
- Connected each monitor to the GPU by themselves to test. Are both working alone or is it just one?
- Have you tested all the ports just to confirm its not a faulty port issue
- Tried another cable/adapter