ASUS 4890

When the chips are down

The previous flagship single-core card from ATI was the 4870, and that was based around the RV770. As a graphics chip it was everything we could really ask for; a small die size for affordability and lower heat, and decent overclocking potential for extra gain. It had 956 million transistors, a core clock of 750MHz, and 800 stream processors.

ATI has taken this existing design, and based its new card around it - the RV790XT. This core has the same amount of stream processors, the same 55nm manufacturing process and runs with the same 256-bit memory bus, so what is different? The answer, of course, is in the clocks.

One of the main benefits of a mature manufacturing process in silicon chips (for example the Intel Core 2 CPU line) is that you're eventually left with a very high percentage of reliable, well-performing chips. ATI's had a lot of time to perfect the process by now, and this shows in the extra 100MHz core clock, and 75MHz memory clock that ATI have added to the card.

This speed increase gives a huge bump in theoretical memory bandwidth (adding 1.6 GigaPixels per second), as well as compute performance of 1.36 Teraflops. That's 10¹² FLoating point Operations Per Second, which is incredible. How did they get this huge increase - voodoo?

RV790XT core, all naked and such.