MaximumPC 2008 04

reviews TESTED. REVIEWED. VERDICTIZED

A

MD’s Radeon HD 3870 is a fi ne GPU for

the money. It doesn’t outperform Nvidia’s

GeForce 8800 GTX, and it lags far behind

the extravagant 8800 Ultra, but it does deliver

a phenom— er, make that a tremendous price/

performance ratio.

So what happens when you put two of

these parts—each with its own 512MB frame

buffer—on a single board? You get a Radeon

R3870 X2. The result isn’t as spectacular as

you’d expect, but MSI’s implementation delivers

plenty of bang for the buck. This card isn’t an

Ultra killer by any means, but with a price tag of

just $450, it doesn’t need to be.

There’s nothing mysterious about the R3870

X2—the two GPUs are exactly the same as those

on a single-GPU card. Each one has 320 stream

processors, a 256-bit memory interface, support for

AMD’s Unifi ed Video Decoder (for offl oading HD and

Blu-ray video-decoding

from the host CPU), and

dual-link DVI with HDCP

on both links (to sup-

port the native resolu-

tion of 30-inch LCD panels).

If you care as much about high-defi nition video

decoding as you care about gaming, you probably

know that neither Nvidia’s 8800 GTX nor its 8800

Ultra supports those last two features. And unlike

Nvidia’s new GPUs that do fully offl oad HD video

decoding, the R3870 X2 supports the incremental

updates to DirectX: Direct3D 10.1 and Shader

Model 4.1 (although we believe this support to be

unimportant right now).

MSI set the GPUs’ cores to run at 828MHz

and the memory at 955MHz, a fraction faster

than AMD’s reference-design specs of 825MHz

and 900MHz, respectively. As with AMD’s 3870

X2 reference design, MSI’s board has two 512MB

frame buffers, one for each GPU. AMD’s reference

design and MSI’s implementation both use GDDR3

memory, compared to the GDDR4 memory found

on single-GPU 3870 cards. AMD tells us there’s

nothing about the design that would prevent its

board partners from using GDDR4 memory or from

increasing the size of the frame buffers (although

we suspect there wouldn’t be a tremendous differ-

ence in performance from either design change).

A PCI Express 1.1 bridge chip sitting between

the two processors effectively creates CrossFire on

the card (with 16 bi-directional lanes for each GPU)

without the need for a CrossFire chipset on the

motherboard. There is, however, a single intercon-

nect that will allow you to build a CrossFireX rig

with four 3870 GPUs onboard, but that does require

a CrossFire chipset. The board itself supports PCI

Express 2.0, but AMD tells us that putting a PCI

Express 2.0 bridge chip between the two GPUs

would have delayed the product and wouldn’t have

yielded much of a performance

boost anyway.

Having all the compo-

nents on a single board strikes

us as a much more elegant

solution than sandwiching

boards together, which Nvidia

did with its since-discontinued

7950 GX2. It also allows AMD

to use a single cooler, which is

located at the very end of the

board and exhausts outside

the case, for both GPUs and

both frame buffers.

Having a single fan not only renders the

card nearly as quiet as a single-GPU confi guration

but also avoids the need for twice the electrical

power. The R3870 has two auxiliary power sockets

MSI R3870 X2 T2DIG

Can a double shot of Radeon outdo a single dose of Ultra?

The dual Radeon 3870 GPUs require a lot of board real estate,

which means the Radeon 3870 X2 won’t fit in every case

(although it’s no longer than Nvidia’s GeForce 8800 Ultra).

72 MAXIMUMPC | APR 08 | http://www.maximumpc.com

MSI RADEON

3870 X2

XFX GEFORCE

8800 ULTRA

Best scores are bolded. AMD-based cards tested with an Intel D975BX2 moth-

erboard; Nvidia-based cards tested with an EVGA 680i SLI motherboard. Intel

2.93GHz Core 2 Extreme X6800 CPUs and 2GB of Corsair DDR RAM used in

both scenarios. Benchmarks performed on ViewSonic VP2330wb monitors.

WINDOWS XP

3DMARK06 GAME 1 (FPS) 47.6 35.2

3DMARK06 GAME 2 (FPS) 42.1 31.7

CRYSIS (DX9) (FPS) 23.1 38.6

UNREAL TOURNAMENT 3 (FPS) 86.5 97.6

WINDOWS VISTA

3DMARK06 GAME 1 (FPS) 46.4 34.3

3DMARK06 GAME 2 (FPS) 41.9 30.9

CRYSIS (DX9) (FPS) 26.7 30.1

UNREAL TOURNAMENT 3 (FPS) 68.4 75.4

BENCHMARKS

GPU Radeon HD 3870 (x2)

GPU MANUFACTURING 55nm

PROCESS

MEMORY 512 MB GDDR3 (X2)

FORM FACTOR Dual Slot

DISPLAY INTERFACE Dual-Link DVI with HDCP on both links

PCI EXPRESS SUPPORT 2.0 on the motherboard; 1.1 on the card

DIRECTX SUPPORT DIRECT3D 10.1; Shader model 4.1

POWER SOCKETS One six-pin, one eight-pin

SPECS