MaximumPC 2004 12

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x16 slots as x8. Why not operate both

slots at true x16 modes? nVidia says

there are two reasons. The fi rst is that

there is no need for today’s—and

probably even tomorrow’s—hardware

to require that much bandwidth.

The second reason is the electrical

challenge of building a chipset

with 32 or more PCI Express lanes;

extra lanes require the chipset to

have additional contact pads—the

electrical contact points that must be

soldered to the motherboard. With

32 lanes, the amount of contact

points would make the chipset pretty

unwieldy, size-wise, which may

explain why no PCI Express chipset

we’ve seen to date supports more

than 20 PCI Express lanes.

Despite rumors that SLI will

require identical PCB boards and

chip versions to operate, nVidia

offi cials tell Maximum PC that the

only requirement for pairing up

videocards is that the cards be of

the same family. That is, you will

have to mate a 6800 GT with a 6800

GT—not a 6800 Ultra.

The nForce4 chipset will be

introduced in three versions: an

SLI version that supports all the

chipset’s features, an Ultra version

that lacks SLI, and a stripped

“mainstream” version that’s so basic

you won’t even get the SATA 3GB/s

support or the fi rewall.

When paired with the

MSI K8N Diamond, this

card lets you configure

the board to operate as a

single x16 or dual-x8 PCI-E

for SLI graphics cards.

The four SATA ports
and two PATA ports
can combine forces
for a jumbo RAID
configuration.

The nForce4 chipset

continues to be a

single-chip solution.

Any Socket 939

processor should work

with the nForce4 SLI.

Whither VIA?

n6idias comPetitor makes

big Plans for PC) EXPress

VIA isn’t standing still while nVidia

rolls out its fancy-pants hardware.

While we’ve yet to see any actual

parts, the company was the fi rst to

announce a PCI Express chipset

for the Athlon 64/FX platform with

the K8T890.

Unlike nVidia’s ultra-low latency

single-chip solution, the K8T890 is a

traditional north bridge/south bridge

confi guration. VIA makes 20 PCI

Express lanes available in the north

bridge and two in the south bridge,

which the company says allows

motherboard vendors to make fl exible

choices, like plumbing LAN or an

HDTV tuner directly to a PCI Express

lane in the north bridge. VIA also says

it will support dual PCI Express cards

in a Pro version of the chipset, but

it’s not clear yet if the company has

the blessing of its arch-rival nVidia.

Finally, a version of the chipset that

supports dual video cards for the

Pentium 4 called the PT894 Pro is also

in the works for later this year.

What’s new in nForce

2004 MA XIM 13 UMPC

W

e’re so accustomed to seeing microproces-

sors and memory chips get faster, cheaper, and

smaller that it’s easy to believe Moore’s law applies

equally to all chips. But there’s an interesting excep-

tion: image sensors for digital cameras.

Someone in an online forum recently questioned

the wisdom of buying a 6- or 8-megapixel camera right

now. His reasoning was that Moore’s law would rapidly

make them obsolete by bringing us 12- and 16-mega-

pixel cameras for roughly the same price in 18 months

or so. After all, isn’t that the effect of Moore’s law: The

transistor density of chips doubles every 18 months?

Alas, there are two problems with his reasoning.

First, Moore’s law doesn’t really work as advertised,

even with microprocessors. However, that’s a subject

for a future column. More to the point: Moore’s law isn’t

necessarily helping image sensors, because they don’t

always get better as they shrink in size and increase in

density. In fact, they’re starting to get worse.

Compare the latest 6-megapixel digital SLRs from

Canon and Nikon with the latest 8-megapixel digi-

cams from the same two companies and from Konica

Minolta, Olympus, and Sony. If pixels were all that

mattered, the digicams would be clearly superior to

the DSLRs—but they aren’t. The DSLRs produce better

images, especially at higher sensitivity (ISO) settings,

despite having sensors with 25 percent fewer pixels.

Mainly, the DSLR pictures are better because they’re

less “noisy,” also referred to as grainy. They’re less

noisy because DSLRs have larger image sensors with

much bigger sensor sites or “light wells,” so they cap-

ture more photons per pixel than the digicams do.

Taking advantage of Moore’s law to shrink an

image-sensor chip and increase the density of its

sensor sites has become a disadvantage. A smaller,

denser imaging chip has more pixels but is less sen-

sitive and noisier. The key to making better digital

cameras is to fabricate larger sensor chips that have

room for more of the bigger sensor sites. DSLRs with

full-frame (35mm-size) sensors, like the 11-megapixel

Canon EOS-1Ds, yield pictures that rival those from

medium-format film cameras. Unfortunately, making

larger chips runs counter to the goal of Moore’s law,

which is to make smaller and denser chips.

Nevertheless, Moore’s law helps digital cameras

in other ways. Sometimes it’s possible to reduce man-

ufacturing costs by making image sensors using older,

amortized chip-fabrication technology instead of the

latest, most expensive technology. Also, other chips in

digital cameras definitely benefit from Moore’s law—

particularly the microprocessors that manipulate and

compress each picture before saving it on the memory

card. But the heart of a digital camera, its image sen-

sor, defies the famous law.

Digital Cameras

Defy Moore’s Law

Tom Halfhill was formerly a senior editor for Byte magazine and

now an analyst for Microprocessor Report.

FAST FORWARD BY TOM R. HALFHILL

Quick Start

DECEMBER 2004 MA XIMUMPC 15