RE: Optiplex 745 sff Graphics and Power supply upgrade
The HD 5450 will work. However, I would shop around for the better HD 6450. You do not need a power supply upgrade for either card and that power supply will not fit anyway. The HD 5450 is only a 20 watt card and the HD 6450 is a 30 watt card. I used the HD 6450 in the 745 SFF for quite sometime and never had any issues. The 275 watt PSU is more than enough for these video cards. The manufacturer's power supply requirement of a 400 watt unit is simply overblown. It is completely unnecessary especially when you know the actual power consumption of these cards as I stated. Again, my choice would be the HD 6450 since if offers better performance for basically the same upfront cost HERE. I don't care too much for rebates and the HD 6450 has better compatibility with Dell systems compared to the HD 5450.