I can almost 100% confirm that the psu in the optiplex will not have the power connector for the PCIe gfx card and will not have enough grunt to power it anyway. I'm not 100% on modern gfx cards, nor am I 100% on modern games (! am not a gamer) but I have worked with a lot of dells and those model optiplex are pretty old (by PC standards). You may be able to find a half-height gfx card that doesn't need the extra power connector, but I have to concur with the other advice offered. If your serious about gaming, you need a serious games machine
