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ATi Radeon X1900XT Retail Cards : ASUS & Sapphire

ATi Radeon X1900XT is the long awaited successor to the older X1800XT. Previously known as the R580, the X1900XT features a whopping 48 Pixel Shader unit architecture – 3 times more than what the X1800XT offers. In this review, we take a look at retail cards from ASUS and Sapphire, and then stack them up against competing cards from NVIDIA. Can ATi regain its long lost performance throne?


ATi Radeon X1800 (R520) series are supposed to be products for Spring last
year but due to some design issues that hinder its release, the launch was
delayed till October. This allows NVIDIA to gain more market share in all fronts
with their already successful GeForce 6 series and the introduction of GeForce
7800 series in June last year. To make the matter worse, it was only until
December that users can actually get their hands on the X1800 retail cards in
stores that gave NVIDIA another chance to come out with the 7800 GTX 512MB
versions to secure the performance crown when ATi thought they had a chance.
Also while performance of the X1800XT 512MB may just be
on par if not slightly better than the GeForce 7800 GTX 256MB, the ATi card is
usually priced higher. Sadly, this gives no competitive edge for ATi at all.

Although the delay for the R520 was a long and excruciating one, the
R&D work and preparations on the its successor, R580 did not fall behind.
Therefore it is only barely 2 months after the debut of the X1800 series that
ATi decided to forgo it and concentrate their efforts on the Radeon X1900 series
that hopefully will give them a better position and competitive edge over
NVIDIA. As such, the Radeon X1800 cards which barely make their way on the
retail shelves for 2 months reached EOL instantly.

Today, the spotlight shines on ATi’s next top end VPU, the Radeon X1900
Formally known as R580, this new chip has sure some very promising
specifications that could well dethrone NVIDIA’s absolute fastest card – the
GeForce 7800 GTX 512MB. While only overclocked versions of X1800XTs could barely
touch the 7800GTX 512 in just certain scenarios, the R580 sure has enough
firepower that can dominate the charts. But away from the paper specifications,
what is most important is the fact that if ATi actually have these cards on sale
today, right on the launch day itself. It has been a long time since their
recent fiasco of not being able to have retail stocks on launch day itself.
After all the trashing from both the consumers and the media alike, ATi has
finally delivered their goods – this time round on time! The Radeon X1900 cards
are available at e-tail and retail stores.

Products At Launch

  • Radeon X1900 XTX : 650MHz Core, 775MHz Memory, 512MB GDDR3, MRSP $ 649
  • Radeon X1900 XT : 625MHz Core, 725MHz Memory, 512MB GDDR3, MSRP $ 549
  • Radeon X1900 Crossfire : 625MHz Core, 725MHz Memory, 512MB GDDR3, MSRP
    $ 599
  • All-In-Wonder Radeon X1900 : 500MHz Core, 480MHz Memory, 512MB GDDR3, MSRP
    $ 449


Architecture At Glance

The number of transistors grew to a whopping 384M on the R580, some 63M more
than the R520 built on TSMC’s 90nm process technology. This denotes some
sizeable changes in the architecture and mostly on the tripling the pixel
shaders units. The design of the R580 series doesn’t take long for the R&D team
since it retains most of the goodness of the R520. While the older
X1800XT only carries 16 of these pixel shader units, the new X1900XT carries a
whopping amount of 48 pixel shader units. However, the number of Texture Mapping
Units (TMUs), Raster Operation Output units (ROPs) remains unchanged at 16 as
well as 8 Vertex Shader units on both R520 and R580. With 48 shader cores, 
the R580 is capable up to 48 Vector MADD/ADD ALUs in parallel. However, the
number of maximum threads in flight still stood at 512.

There are also minor but important tweaking to the architecture to improve
its performance and efficiency. The amount of Hierarchical Z buffer size on the
R580 has been increased 50% to store more pixel data so we can expect better
performance at higher resolutions. Also the inclusion of Fetch4 capability
allows acceleration of the filtering of shadow maps by allowing 4 values from
adjacent addresses to be drawn simultaneously instead of one thereby increasing
the texture sampling rates greatly. This is similar to Percentage Closer
Filtering (PCF) method on the NVIDIA GPUs.


Other Physical Differences

The new X1900XTs (and X1900XTX) comes with blistering
fast 1.1ns GDDR3 memory. However, these new X1900XTs are only clocked at a
modest 1.4GHz on the memory, even slower then the default 1.5GHz found on older
X1800XT. The lowering of memory clock speeds might well due to tighter memory
latencies on the X1900XTs. With these 2 key differences between the X1800XT and the X1900XT, there
very minimal differences between the both. Since ATi had made the R580 chip pin
to pin compatible with the older RX180XT cards, makers are expected to have
similar PCB layouts between X1800XT and X1900XT. However, upon our closer
inspection, we found that power regulating portion of the card is slightly
modified to include more VRMs to supply more current. With this aside, both the
X1800XT and the X1900XT share similar physique. We’ll talk more about the
cards in the coming pages.

One of the first cards to arrive here is the ASUS
EAX1900XT. With it’s trademark gigantic box, the EAX1900XT’s packaging design
does not differ much from the older EAX1800XT. Yes, for those who want it,
it’s on retail shelves now!

The other X1900XT that was sent to us, the Sapphire Radeon
X1900XT. Like the ASUS card, this is a retail product and could be bought off
shelves today.

As the R580 core requires more current to operate, the X1900XT
cards are equipped with more VRMs (the row of black square components in this
picture) which would supply the additional current to the core.

Here’s some quick specifications on the Radeon X1900XT:

Processing Unit

ATi Radeon
X1900XT (R580)


PCI Express


GDDR3 1.1ns, Samsung K4J52324QC-BJ11

Mapping Units

16 TMU units

Rendering Operation Output Units

16 ROP units

Pixel Shader
Processor Units

48 Pixel Shader Processor units


8 Vertex


(Token Ring Memory Bus)

Core Clock

625 MHz

Memory Clock

1450 MHz



Max Resolution

2048 x 1536
@ 85Hz

Rear I/O Ports

2x DVI, 1x
S-Video / TV-Out


1X 6pin
PCIe Power Connector Required

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