Optiplex 755 DT requires low profile card or card riser, which is very difficult to find, so your choice
http://www.newegg.com/Product/Product.aspx?Item=N82E16814202052 is this correct, would not fit, power wise it would work.
This card a bit more expensive, MSI N750ti-2GD5TLP GeForce GTX 750 Ti 2GB 128-Bit GDDR5, but stronger and will fit and work in your PC with an existing power supply, which is
280 watt.
Anything else I can help you with?
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