Introduction

In the months leading up to the eventual release of AMD’s Radeon HD 2900 XT, rumors and pictures surfaced of several mysterious cards which ultimately weren’t released on the 2900 XT’s launch day last May. Arguably the most remarkable of these prototype Radeon HD 2900 cards was the 12” card with 1GB of GDDR4 memory. Many referred to it as the Radeon HD 2900 XTX as its memory was clocked at 1.0GHz; over 150MHz higher than the Radeon HD 2900 XT.

At 12” long, the card would have been bigger than anything else on the market, including the GeForce 8800 GTX, and as such it would have had a hard time fitting in some cases. As a result, the card was intended to be sold by system builders only, who would be able to properly house the card in a case that was large enough to accommodate it.

Diamond Viper Radeon HD 2900 XT 1GB

The GeForce 8800 GTX and Viper Radeon HD 2900 XT 1GB

512MB AMD card up top, Diamond 1GB card bottom

Ultimately though system builders passed on the 12” card – it was just too big and ran too hot, despite its unique cooling. Instead they opted to wait for ATI’s 9” version. The 9” card runs at the same speeds as the 12” card, only it ships with the same PCB and cooling found on the Radeon HD 2900 XT 512MB. Basically you get all the benefits found in the original 12” card, only in the smaller form factor of ATI’s existing 9” card.

We recently got our hands on one of these hot little items manufactured by Diamond Multimedia, the Diamond Viper Radeon HD 2900 XT 1GB.

The GeForce 8800 GTS 640MB and Radeon HD 2900 XT 1GB

Diamond Viper 1GB cards

Diamond Viper 1GB card and AMD Radeon HD 2900 XT 512MB

Diamond is currently the exclusive manufacturer of these 1GB cards, so you won’t find these cards from board partners like PowerColor and Sapphire, in fact, you won’t even find these cards being produced by AMD: this is Diamond’s baby at the moment.

Diamond has been shipping these cards to the following system builders since mid-June:

Biohazard Computer Systems, Inc.
http://www.biohazard-computers.com/
Extreme PC
http://www.extreme-pc.ca/default.asp?currency=ca&force=1
Falcon North West
http://www.falcon-nw.com/
Maingear
http://www.maingear.com/
Memory Express
http://www.memoryexpress.com/
NCIX
http://www.ncix.com/
Smooth Creations
http://www.smoothcreations.com/
Velocity Micro
http://www.velocitymicro.com/
Vigor
http://www.vigorgaming.com/
XI
http://www.xicomputer.com/

GeForce 8800 GTX and Radeon HD 2900 XT 1GB both have dual power connections

Front of the cards

512MB card and 1GB card

Up to this point, the Diamond Viper Radeon HD 2900 XT 1GB was only available from these aforementioned system vendors – you couldn’t buy one at an online outlet like Newegg or Zipzoomfly. But due to a surge in demand, Diamond has decided to offer it in retail form and e-tailers should begin carrying the card online later this week. Officially the card will carry an MSRP of $549, making it around $150 more than the Radeon HD 2900 XT 512MB and placing it solidly in GeForce 8800 GTX territory.

The question is, how does the card perform with the addition of 1GB of 1.0GHz GDDR4 memory? That’s what we’re here today to figure out. Let’s take a look at how the Diamond Viper Radeon HD 2900 XT 1GB stacks up to its competitors:

High-end Specifications Comparison
	Diamond Viper Radeon HD 2900 XT 1GB	Radeon HD 2900 XT 512MB	GeForce 8800 GTX	GeForce 8800 GTS 640MB
Core Clock Speed (MHz)	745	740	575	500
Stream Processor Clock Speed (MHz)	745	740	1350	1200
# of Stream Processors	320	320	128	96
Memory Interface	512-bit	512-bit	384-bit	320-bit
Memory Size	1GB	512MB	768MB	640MB
Effective Memory Clock (MHz)	2000	1650	1800	1600
Memory Bandwidth (GB/sec)	128	105.6	86.4	64
MSRP	$549	$400	$550-$600+	$400

Notes

Not only does Diamond’s Viper Radeon HD 2900 XT 1GB sport more memory than your typical Radeon HD 2900 XT card, as we outlined earlier, it’s packing 1.0GHz (2.0GHz effective) memory. As a result, the memory subsystem is capable of delivering up to 128GB/sec of peak bandwidth to the graphics core. That’s an impressive figure that no other GPU on the market can match, but this number can be a little deceiving. We’ll discuss this in more depth on the next page.

The graphics core itself carries over largely unchanged from the 512MB Radeon HD 2900 XT. The chip runs at 745MHz, 5MHz higher than the 512MB GPU. That’s not really a lot honestly, especially considering the overclocking potential R600 has demonstrated in the past – these GPUs can really be pushed. It’s too bad these GPUs weren’t pushed to say, 800MHz or so.