LOSTCIRCUITS

107 Million Transistors in 150 nm fab Process For The R300

Inside the core, we are looking at 110 million transistors that are pushing performance of the R300 to new levels. Performance in this case does not mean that anything will run faster at low resolution with all features turned off, what it means is that high-resolutions like 1600 x 1200 running at 4 x antialiasing combined with 16 x anisotropic filtering will remain playable under all circumstances with all current games.

RADEON 9700. Because of the high power demand of the core, the card is equipped with an auxiliary power connector (arrow)

From a technical standpoint, the hottest and most exciting aspects of the R9700 are the raw power features packed onto the die. Manufactured in Taiwan by TSMC using 0.15 um technology, the core of the R300 still runs at 1.5V with the equivalent power draw and heat dissipation. The transition to a 130 nm process was originally planned to coincide with the launch of the R300 core, however, the technology is still to fragile, too many resources are further occupied at TSMC and overall, the additional potential gains were not worth the risk involved in combining new, uncharted technology with a new process which would have exponentially increased the possible pitfalls.

The side effect of the delayed launch of the 130 nm process is increased power demand that actually exceeds the AGP 3.0 specifications and, therefore, the RADEON 9700 requires external power, reminiscent of the 3dfx VooDoo5. Upping the core voltage to levels that require more power, however, allows to increase the clock speed beyond the 200 + MHz that the VP10 and the Parhelia are stuck with for the time being.

The Quad-Channel memory interface of the R300

The memory interface has increased to 256-bit width to ensure enough bandwidth from the Local Frame Buffer (LFB) to the R300 core. At the announced frequency of 600 mbps (mebabit/sec/pin) the wide interface will deliver no less than 19.2 GB/sec total bandwith, variations in memory speed will allow to push the 20 GB/s barrier.

The memory interface is subdivided into 4 independent memory channels (A-D) of 64 bit width each, linked via crossbar architecture to the individual DDR memory controllers (#1-#4 + AGP controller). This massive amount of bandwidth will be required to handle some of the upcoming games like Doom 3 with textures in excess of 80 MB.

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