You have a 400w PSU in a 755 SFF?  A 400w PSU can easily power a 75w card, but you may have heat issues in the SFF.  And yes, the GT 730 will work. Other cards that will also work: [IMAGE]  
hi ... I'm using OptiPlex 755 sff And I decided to upgrade itsome people says gt 730 is good for 755 but how? its want 38w and and my PCIe slot is 25w onlyBut I searched and found some people saying that PCIe slot with 25w can up to 75wis this real? my Power supply unit is 400w
can i use gpu with 38 tdp in 25w PCIe??