OK. That would mean you have the Mini Tower APFC version (looking at your 305w PSU aswell). Your PSU's max combined 12v output should be 240w.
I couldn't find anywhere about any power limited slots, or PCIe connectors/MOLEX connectors, so I am led to believe the motherboard's PCIe x16 slot is not power limited (it can draw 75w) and no PCIe connectors / molex connectors to adapt from.
EDIT: With that PSU model provided, I can confirm there are no PCIe 6 pin connectors.
So probably the best you can get would be a GTX 1050ti that has a <= 75w TPD and does not need PCIe connectors.