Board analysis (cont’d)

The cooling

Besides the Radeon HD 2900 XT’s unusual power requirements, the other feature enthusiasts have been talking about is the Radeon 2900 XT’s new cooling unit. As you can see in the photos, it’s nothing like the cooler ATI employed previously on the Radeon X1950 XTX, while the card does rely on a ducted cooling design, and the board’s fan does blow hot air outside your system case, it’s a much larger cooler.

AMD now uses two heat pipes (versus one on the X1950 XTX), while a longer heatsink is responsible for keeping the heat pipes cool.

In its current form, AMD’s cooler is quite loud, but we wouldn’t be surprised if this is tweaked with a subsequent driver release. Part of the reason why we think this could be adjusted in the future is because ATI has done this before with the Radeon X1800 XT/XL and X1900 XT/XTX. Initially the fans on these cards ran ridiculously loud, but eventually ATI tweaked them so they ran at more reasonable levels. Another reason why we say this is because the 2900 XT fan currently only runs at two basic settings (a barely audible low setting and a much louder high setting) that leaves a lots of room for AMD to tweak the RPMs if they desire to do so. As you’ll see in our temperature testing, the GPU doesn’t get that hot under full load in large part because the fan spins at such high RPMs.

Hopefully with a little bit of tweaking on AMD’s part the fan can be adjusted to run quieter without affecting temperature too drastically. Personally, we think the reason why AMD decided to run the fan speeds so high is to keep their power consumption levels down. During AMD’s Editor’s Day event it was revealed that the Radeon 2900 XT’s power consumption depended greatly on its temperature. Referring back to our notes, it was revealed that “the ambient temp the GPU runs at will very much affect the amount of power the board consumes”. Quite simply, the hotter the board runs, the more power it will draw.

This all goes back to the way Radeon 2900 XT GPUs are binned. Since there is no XTX SKU, all R600 chips are being used in the Radoen HD 2900 XT. Normally the chips that consume the least power and generate the least heat would go into the XTX SKU, but since ATI was never able to get R600’s power consumption under control, the XTX SKU no longer exists and all R600 chips are going into XTs. As a result, we were warned that there could be a lot of variance in how much power different Radeon HD 2900 XT cards consumed, and to keep temps down in order to keep power consumption in check. As it stands now ATI runs the fan on the Radeon HD 2900 XT at higher RPMs in order to keep temps, and thus power consumption down to manageable levels. As a result though, the board generates considerably more noise than the GeForce 8800 GTS/GTX. In fact, under load two GeForce 8800 cards generate less noise than one Radeon HD 2900 XT.

VIVO and Valve returns to offer another game bundle

One feature that ATI, and now AMD continues to provide in their high-end cards is VIVO (video-in/video-out). The Radeon HD 2900 XT is no exception: all cards will support VIVO. In fact, ATI has replaced the venerable Rage Theater chip used previously to provide this functionality with their newer Theater 200 chip.

Another feature that will be universal to all Radeon HD 2900 XT cards is the game bundle. Like the Radeon 9800 XT launch, ATI has once again partnered with Valve to deliver an excellent game bundle. In this case, all cards will ship with the Black Box Edition of Half-Life 2, which not only includes the latest chapter in Valve’s Half-Life 2 storyline, Half-Life 2 Episode Two, but also includes Portal and Team Fortress 2.

Sapphire’s Radeon HD 2900 XT card

Sapphire was the first AMD board partner to get a final, shipping retail card in our hands, and will likely be first to market with cards at e-tail right alongside AMD’s own card.

As you can see, Sapphire’s Radeon HD 2900 XT card is based entirely on the reference board design for the Radeon HD 2900 XT, literally the only difference between the two cards is the sticker on the fan. Sapphire ships their Radeon HD 2900 XT card with everything you’d need to get up and running, including the HDMI adapter, CrossFire cable, VIVO cable, component video cable, and two DVI adapters. Meanwhile on the software side Sapphire includes DVD playback software, the Half-Life 2 Black Box voucher and a copy of the Pro version of 3DMark 06.

But Sapphire isn’t sticking to just one SKU for the Radeon HD 2900 XT. For enthusiasts looking for more performance, Sapphire will also be offering a Toxic Edition of the card. The Sapphire Radeon HD 2900 XT Toxic will ship with more memory than the standard Radeon HD 2900 XT – 1GB of GDDR3, and both the graphics core and memory will be overclocked out-of-the-box. Sapphire’s currently projecting an OC of 15% for the graphics core, and 50-70MHz for the board’s memory.

If that weren’t enough, the Toxic will also be liquid cooled. Shipping with the card is an external water cooling unit which will require two empty 5.25” drive bays. Keeping everything cool will be a large fan outfitted with blue LEDs that will spin anywhere from 1600-2400 RPMs. The cooling system is completely modular, meaning you can add an additional Radeon HD 2900 XT Toxic card for CrossFire, or even a 3rd-party CPU waterblock for cooling your processor.

The Toxic card is expected to ship sometime in June, and we’ll definitely be keeping our eyes out for it.

A new driver arrives

Late last week AMD submitted a pre-release alpha driver which delivered their new 12x and 24x AA modes, as well as providing performance enhancements in Oblivion and other apps with HDR lighting. According to AMD:

“The driver team has been working on improving adaptive AA performance over the existing press driver with a new intelligent algorithm that increases FPS while applying similar image quality to that of the first press driver. In some cases, such as Oblivion, we're seeing performance that is several times faster than what was seen before using the new adaptive AA algorithm. We've also done some new optimizations for HDR applications that in general result in a 5-30% increase in performance. This is an absolutely incredible performance increase within just a few short weeks of the initial driver build, and a testament to the programmable capabilities of the architecture.”

Based on this, we decided to re-run our tests with the new driver. In the subsequent graphs you’ll see the Radeon HD 2900 XT running with this driver labeled as “alphadriver”. Unfortunately by conducting these tests we weren’t able to take a closer look at the image quality and performance of AMD’s new AA modes, but we will take a look at that shortly in a subsequent article.