MaximumPC 2005 12

reviewsTESTED. REVIEWED. VERDICTIZED

78 MA XIMUMPC DECEMBER 2005

W

ith prices for natural gas and

home-heating oil spiraling out

of control, upgraders looking for

a hot new videocard will want to take a

look at ATI’s new Radeon X1800 XT. This

card generates so much heat it could

replace a small furnace.

OK, we’re exaggerating. But the X1800

XT really does get warm. In spite of its high

temperature, the X1800 XT is clearly supe-

rior to ATI’s previous top-of-the-line part.

For starters, the entire X1000 series finally

supports Microsoft’s Shader Model 3.0. This

development should dissolve any reluctance

game developers have had about embrac-

ing Shader Model 3.0, which should result in

more visually sophis-

ticated games hitting

the market.

ATI tells us its

decision to manu-

facture the X1000

series of GPUs using

a 90nm process

enabled a dramatic

increase in core clock

speeds: the X1800 XT

runs at a staggering

625MHz, compared

with the Radeon X850

XT Platinum Edition’s

547MHz core, and

the 430MHz core

on a stock GeForce

7800 GTX. But what’s

really astounding is

the fact that ATI has

cranked the clock on

the memory to a blis-

tering 750MHz.

When we re-

viewed nVidia’s GeForce 7800 GTX back in

our September issue, we quipped that “24 is

the new 16, when it comes to pixel pipelines.”

ATI must not have gotten that memo, because

the Radeon X1800 XT features only 16 pixel

pipes. But then, perhaps it’s not the number

of pipes, but what a GPU does with those

pipes that really matters. (Or maybe it’s simply

a matter of driving the whole enchilada at

unheard-of clock speeds.)

ATI offers the X1800 XT with two memory

configurations:

256MB for $500

and the $550,

512MB version

reviewed here.

When the 512MB

version of the

X800 XL shipped a few months back, ATI

reps told us game developers were chomp-

ing at the bit to gain access to larger frame

buffers. Although we’re skeptical of that

claim, the $50 price delta separating the 256-

and 512MB versions is a smokin’ deal.

ATI’s new “ring bus” memory control-

ler—a third feature common to the X1000

series—is almost more interesting than the

GPU’s process size. Rumors that had ATI’s

new GPUs boasting a 512-bit memory

architecture were only half right: As imple-

mented in the X1800 cards, the memory

controller is surrounded by two 256-bit

rings. Data from read and write operations

runs in opposite directions around these

rings, arriving at ring “stops” (one for each

pair of memory channels) that are linked

directly to the chip’s memory interface.

ATI maintains that this design enabled an

increase to memory clock speeds while

simultaneously reducing latency. Be that as

it may, GDDR3 memory is GDDR3 memory,

so we’ll be watching closely to see if ATI

can actually acquire enough 750MHz chips

to satisfy demand.

So what about performance? In our game

benchmarks, the X1800 XT edged past XFX’s

GeForce 7800 GTX on four

out of seven tests. Fans of

Doom 3 (and Quake 4, and

all the other games that will

be based on that engine),

however, will want to consid-

er this card’s poor showing

with that game. Aside from

the disappointing Doom 3

score, the card performs

well. If ATI can do this well

with just 16 pipes, imagine

what it could have done with

a 24- or 32-pipe processor.

We’re severely disap-

pointed with this card’s

video performance: ATI

seems to have taken one step forward and

a step-and-a-half back. The step forward is

color saturation that’s clearly superior to that

of both ATI’s previous-generation cards and

nVidia’s latest offering. The HQV composite

score of 51, on the other hand, is 14 points

lower than what ATI’s X850 XT Platinum

Edition earned in the videocard roundup we

published in November (and it’s a whopping

32 points lower than that of the 7800 GTX).

What happened? The X1800 XT actually per-

formed dramatically better on most of these

benchmark tests—including jaggies compen-

sation and 3:2 pull-down

Screaming clock detection—but when it

speeds require a

loud, two-slot cool-

ing solution.

ATI Radeon

X1800 XT

Too little, too late, too hot

Aside from the white heatsink, ATI’s Radeon X1800 XT looks

amazingly like ATI’s X850 XT Platinum Edition.

SPECS

ATI XFX ATI

X1800 XT 7800 GTX X850 PE

Best scores in each category are bolded. All benchmarks are run on our Athlon FX-55 test system,

which includes an nForce4 SLI motherboard and 2GB of DDR SDRAM. Halo 1.06 tested at 1600x1200

with sound disabled. Doom 3 tested at High Quality 1600x1200, 4x AA. Far Cry 1.31 and 3DMark

2003 Game2 and Game4 are tested at 1600x1200, 4x AA, and 8x aniso. 3DMark 2003 and 3DMark

2005 are run using default settings. HQV Score is derived from the HQV Benchmark DVD, which

measures the videocard’s performance displaying DVD movies.

BENCHMARKS

GPU ATI Radeon X1800 XT

PIXEL

PIPELINES 16

VERTEX

SHADERS 8

MEMORY 512MB GDDR3

MEMORY

INTERFACE Dual 256-bit

CORE CLOCK 625MHz

MEMORY

CLOCK 750MHz

DOOM3 (FPS) 43.2 56.7 40.2

FAR CRY (FPS) 103.4 84.3 87.1

HALO (FPS) 107.8 107.9 80.2

3DMARK05 9,029 8,054 6,468

3DMARK03 16,654 16,898 13,170

3DMARK03 GAME 2 (FPS) 46.4 37.0 28.4

3DMARK03 GAME 4 (FPS) 60.0 54.9 41.1

HQV SCORE 51 83 65