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ATI's Radeon X850 XT Platinum Edition Preview

by Ryszard Sommefeldt on 30 November 2004, 00:00

Tags: ATi Technologies (NYSE:AMD)

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The worldwide demand for ATI's Radeon X800 XT and X800 XT Platinum Edition SKUs, both on AGP using R420 and PCI-Express using R423, has seemingly been immense. Stocks of each constantly hover around the zero mark, cards snapped up as soon as they're available.

However, if those stock levels are due to ATI's inability to meet demand for whatever reason, using TMSC as their foundry, one possible way for them to rectify that is by switching the silicon process used by that foundry partner, to create the same GPU on a smaller, cheaper process. It costs you less per wafer and you get a larger amount of dies in that same wafer area. In steps ATI's R430.


R430, in its simplest terms, is just R423 (the PCI Express version of R420), a GPU produced on TSMC's 130nm low-K process, on TSMC's 110nm node. Cheaper to produce for a number of reasons and more dies per wafer, you've got a readily available larger supply of GPUs for your customers.

However the most in-constraint, hard-to-find products are on AGP. A new PCI Express product doesn't help ATI or their customers, without a bridge ASIC back to AGP. And ATI don't have that ready yet.

There's also the issue of R430 actually being limited in its final core speed since there's no low-K option on 110nm just yet. So it's maybe not that suited to creating XT and XT PE. So what about a rejig of R423 on 130nm low-K to sort out yield issues?


R480 is R423 with tweaks. Tweaks that ATI are reluctant to go into detail about, but encompass optimising the silicon layout to remove hot spots, implementing self-regulated power management to turn off or idle parts of the core not being used, to reduce heat, and introducing more effective throttling techniques to stop heat-related issues. Able to be clocked higher on TMSC's 130nm low-K node than R423 ever was officially, and with a die size befitting its 160 million transistors, heat is again a paramount consideration for ATI's new GPU. You'll see the physical manifestation of that shortly.


R481, a GPU that appeared on ATI roadmaps recently, appears to be a product to ease ATI's AGP supply woes, assuming that the new tweaked design is easier to produce than R420. R481 is R480 with a native AGP interface, not needing to be bridged back to AGP as R480 would, were it to power any AGP products. That negates the need for RIALTO, ATI's PCI Express-to-AGP bridge solution, and allows high-end AGP SKUs to be produced en masse. Although rumours recently suggest that R481 is either off the roadmap or delayed, leaving consumers lusting after X800 XT and X800 XT PE lovin' on AGP high and dry for a little while longer.

We've committed to asking ATI some difficult questions about availability and AGP product changes, and we'll report back when we have their answers.

Radeon X850 and new X800s

However the updates to the X8-serios are on PCI Express, so to clue you in to what's going on with those products, here's a handy table.

GPUProduct NameFragment PipesVertex UnitsMemory Bus WidthCore SpeedMemory SpeedPrice
R480X850 XT Platinum Edition166256-bit5401180$549
R480X850 XT166256-bit5201080$499
R480X850 PRO126256-bit5201080$399
R430X800 XL166256-bit4001000$349
R430X800126256-bit400700 (128MB)$249

X800 XT PE drops out in name only. X850 XT replaces it at the same clock speeds, using the new GPU. X800 XT is gone as a PCI Express SKU, though.

And the introduction of R430 means that lower-end X8-series products hit PCI Express for the first time. X850 PRO is just X850 XT with a quad set of fragment pipelines disabled, saving you $100. X800 XL slots in as basically a lower speed binned version of X850 XT and X850 XT PE. It uses R430, who's reasonable clock limits might be lower, but for the cheaper cost, ATI don't care and their customers find themselves with a high-performance PCI Express part without spending silly money.

Finally, a chopped R430 creates the first 'plain' X800 to date, debuting on PCI Express and using cheaper DDR memory for $249. So it seems that ATI's heat-focused design with R480 has paid some dividends. Notice the 500/1000 X800 XT(R423) disappearing as the next-to-top product, replaced by R480 at X800 XT PE's old, higher clocks. And the top PEG product gets the highest core and memory clocks of any ATI graphics product to date. Speedy stuff.

That means we've got some new PEG love and a new top dog, sitting pretty at the head of the table. X850 XT Platinum Edition, if you understand the performance of X800 XT Platinum Edition, looks good to enhance ATI's position at the top of the graphics card pile. Is it the fastest consumer graphics card ever created? Turn the page.