Conclusion: The Dell OptiPlex 755 is the hybrid SUV of green PCs. It has more utility than the tiny, small-form-factor PCs (think of them as Toyota Prius or Honda Civic hybrids), but it also consumes bit more power when on. It will serve your users well while saving you money on the energy bills that never seem to end.
Conclusion: Overall, the OptiPlex 755 is a solid, expandable business machine without fancy bells and whistles--the lack of which likely accounts for much of its energy-efficient performance.
Conclusion: We like the trend towards a power saving focus, though there's little we can attribute to this machine that hasn't been used before. Regardless, it's a promising step forward. Performance-wise this machine does well, though the lack of e-SATA and FireWire is a shame.