Hardware Canucks posted a review of the HD 4770 512MB GDDR5 video card.

The HD 4770 is the poster boy for the changing face of ATI. They have forgone the push for a power-hungry monolithic architecture and have instead focused their energies on scalable, more compact GPU cores which can be used for multiple cards in various price ranges. This was first accomplished with the 55nm HD 4800-series and later perfected with the lower end HD 4600 series and more recently the HD 4890 1GB. As technology has progressed, so too has ATI's shift towards a more price and efficiency-conscious manufacturing processes.

ATI Radeon HD 4770 512MB GDDR5 Review