Better than HD 4830?
GDDR5 memory on a mid-range GPUSo where's the performance concession? It lies with the 128-bit-wide memory bus, brought on over from HD 4670, so bandwidth limitations may well come into play at higher resolutions. However, ATI has mitigated many of these by interfacing the bus with GDDR5 memory - previously found on Radeon HD 4870 and HD 4890 - running at an effective 3,200MHz. Do the math and the GPU has over 50GB/s on tap, matching other £75-£100 cards'.
Pragmatism
Pulling some 80W under load, reference boards will ship with a dual-height cooler, going against the single-slot model on the Radeon HD 4850 512MB card. The 40nm process should clock high and the cooler will help keep the GPU relatively cool.
Summary
ATI's looked at the most cost-effective method of producing a decent sub-$100 GPU and has opted to leverage existing R4K technology and use the cutting-edge 40nm fabrication process and high-speed GDDR5, to keep the die-size small.
The HD 4770's vital stats are such that it should beat up on the performance delivered by the Radeon HD 4830. Seeing as it's a more-expensive GPU to produce, the introduction of the new 40nm GPU is surely a harbinger for the HD 4830's demise. Radeon HD 4850, too, isn't safe from the HD 4770.
Assuming the above sentence is borne out by the results, Radeon HD 4770's nomenclature causes a few problems. It should be faster than a 4800-series card, but that doesn't fit in well with ATI's numerical branding. Trouble is, the current line-up is such that it has nowhere to go, numbering-wise, because its 128-bit memory bus doesn't fit in well with other 48x0 GPUs' 256-bit. The vagaries of nomenclature, eh?
NVIDIA's similarly-priced GPUs are the offspring of high-end hardware, and a spate of price-cutting brings their technology firmly into the mid-range spectrum. In essence, ATI's technically-engineered a card to fit into this space but NVIDIA's used the weapon of economics to serve the same end.
