ATI Radeon 4770 Performance Preview

Ever since it was launched last fall, we’ve been huge fans of ATI’s Radeon 4830. The chip is based on the same RV770 core found in the hugely popular Radeon 4850 and Radeon 4870. This gives the GPU a highly capable foundation to build on, and fortunately ATI didn’t cripple it to the point of irrelevance: ATI deactivated two SIMD cores, leaving 640 stream processors, a 256-bit memory interface, and decent clock speeds (575MHz core/900MHz memory).

Overall the Radeon 4830 is a good performer, capable of running most games at 1600x1200 with 4xAA/8xAF (even 8xAA in some cases) and high quality settings with good frame rates. In comparison to its closest competitor from NVIDIA, the GeForce 8800/9800 GT, the Radeon 4830 is pretty even, with each card trading wins in various games. Only under 8xAA does the Radeon 4830 really pull away from the GeForce card.

But as good as the Radeon 4830 is, it does have a slight problem: falling GPU prices. When the Radeon 4830 was originally launched, it was priced at $130. But thanks to falling GPU prices, 4830 cards now sell for as little as $87-$100 online ($77 after rebate). That’s a reduction of over 30%.

While this is great news for consumers looking to upgrade, this isn’t good for ATI’s bottom line. Falling GPU prices reduce their profit margins. And while RV770 isn’t a massive chip, it still isn’t very cost effective for ATI to sell it in a $90 Radeon 4830 card, and with the way prices have been going, the 4830 could be another $10+ less in another month or so.


To address this issue, ATI needed a GPU solution that was custom built from the ground up for this segment of the GPU market. Rather than concoct a purpose-built 4830 ASIC at 55-nm, ATI’s decided to go even smaller, pressing TSMC’s 40-nm manufacturing process into service for their new RV740 GPU.

But a smaller manufacturing process isn’t the only move ATI has made to RV740 to reduce costs, the chip also sports a narrower 128-bit memory interface. To make up for the simpler interface, ATI has decided to integrate speedy GDDR5 memory into RV740: the board ships with the same 800MHz GDDR5 (3.2GHz effective) that was first used on the Radeon 4870 last year. This allows the card to boast very respectable memory bandwidth figures despite its 128-bit interface.

The most impressive part of all though is that thanks to high clock speeds, the RV740-based Radeon 4770 is actually faster than the Radeon 4830, despite its name. It’s actually a little closer in performance to the Radeon 4850 than the 4830! Let’s see what else is new under the hood of this chip…