by February 22, 2006 0 comments

Never in the history of graphics cards have we seen the
kind of activity we did in the past six to eight months.

NVIDIA’s SLI became mainstream, ATi finally managed to
come out with its Crossfire. The NVIDIA gave us full scale x16 SLI. ATi launched
its X1000 range of cards which was more paper launch than anything you might be
able to see in store shelves. NVIDIA was only slightly better. Even though it
did manage to time the G70 launch with ready availability (and in the process,
shook up the way things were done in a big way), its 7800GTX 512 was nothing
more than a paper launch. We are yet to see the mass availability like we have
seen for other cards.

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NV40, G70 What?
When NVIDIA launched its 5xxx series of GPUs, they were hammered by the
corresponding GPUs from ATi. No question, ATi was king of the world as far as
graphics was concerned.

NVIDIA quickly geared up though and launched a new Geforce
G6 series (code name NV40) which catapulted it to graphics fame. You see, the
leap in performance from the 5950 ultra to the 6800 Ultrawas so humongous that
ATi was flummoxed. Even though it did a commendable job with the X800XT, it
really wasn’t much of match for the 6800 Ultra which was the best card around.

Then NVIDIA went ahead and launched 7800 series based on
the G70 GPU. The G70 is a whole new architecture and is phenomenally faster than
the Geforce 6 series we had seen so far. It is in fact inspired from the
graphics processor they have used in the upcoming PlayStation 3. Of course, it
is not the same chip, but NVIDIA told us it is as close an interpretation as
possible. The jump was massive that NVIDIA decided to call it G70 instead of
NV41.Apart from the higher clock speed and a thinner (11nm versus 13nm)
fabrication process, the G70 saw the reintroduction (earlier in NV35 but not in
the NV40 chip) of the mini ALUs to the Pixel Shader. These ALUs significantly
increase the mathematical competence and thus the Pixel Processor speeds. The
G70 has 24 pixel processors and if you do the math, 24 Pixel processors doing 8
instructions at once in a single cycle gives you around 165Gflops. This is
roughly 3 times of what a 6800 Ultra (NV40) could do.

The internal structure of the R520 graphics card from ATi. This card supports Pixel Shader 3.0 with 16 pipelines

In our labs, we have found that the 7800GTX 512 easily
outshines ATi’s X1800XT and has ensured that NVIDIA retains the title of the
fastest card manufacturer for another cycle. However, NVIDIA might have a small
problem: It’s called the R580.

ATi’s R520 and R580
We were once told that whether or not a product is successful, ATi goes back
to the drawing every time they start work on a new card. While we can’t
confirm that, we can tell you that ATi has some really interesting things in the
pipeline (pun intended!)

The current generation of ATi cards, X1000, X1300, X1600,
X1800 and variants, are based on the R520 chipset. ATi had huge amounts of
problems bringing the R520 to the market but it is finally here.

The R520 brought Crossfire, ATi’s answer to NVIDIA’s
SLI technology. Crossfire however didn’t take off as well as SLI did,
primarily because the products were just not available for their fans to buy. In
terms of technology, the R520 is light years ahead of the previous R480 chips.

ATi has done the Graphics engine for the Xbox 360 but the
revolutionary unified shader architecture has not been ported to their R520
chipsets. So the R520 still has separate pixel and vertex shaders.If you look at
the R520 design, you will be able to spot references of R420 and R300 of

However, since the R520 supports Shader Model 3.0,
significant reworking has been done on the pipeline architecture. Note that even
though the architecture is revamped, R520 still is capable of 16 pipelines.The
four Quad Pixel Shader engines get their data from something called the Ultra
Threaded Dispatch Processor. These processors then in turn interact with the
Register Arrays, Stencil cache and are ultimately responsible for creating the
visual effects that you see on screen

The R580
Even though ATi has been beaten fair and square this time, it is already
about to come out with a whole new architecture code named R580.

The R580 based cards will be named X1900 and if the specs
are anything to go buy, ATi could have a winner on its hands.

The differences between various ATi graphics cards
Codename R520


Card X1800XT X1900XTX X1900XT 7800GTX 512
Core Clock 625MHz 695MHz 625MHz 550 MHz
Memory Clock 750MHz 1550MHz 1450MHz 850 MHz

Note here that even though the core clock of the X1900
series is not that much higher that the R520 based cards, the memory clock is
nearly double! The 7800GTX 512 pales in comparison and we think that once the
X1900 series is out, the G70 would’ve been truly beaten.

However, the interesting thing that comes out here is that
if, despite the same core clock, the memory speeds are double, it means that
there are substantial amount of processors (pixel/vertex) which need to be
serviced by the memory and hence it needs to be fast.

We are not able to determine if there is a direct relation
between the doubling of the memory bandwidth and the pixel and vertex processors
but either ways, such high speeds of memory would mean there is are a
significantly increased number of processors.

Currently, the X1800XT has 16 pixel processors. Note that
the 7800GTX 512 has a lower overall clock but since it has 24 pixel pipelines,
it is much faster than the X1800XT. We suspect that the X1900XTX would have at
least 24 pixel pipelines. Couple this with the double memory speeds and you have
one heck of a card!

We are now waiting with baited breath for ATi and NVIDIA to
launch their newer chips. Being avid gamers, we know that you can never have
enough power on your graphics card, and the sooner the newer versions come out,
the better!

Varun Dubey

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