Radeon HD 2900XT is AMD’s latest flagship on the graphics card market and even though not aiming for the performance crown the new series of Radeon cards has shown a great deal of potential. But let’s rewind to the fact that AMD chose to not go for beating NVIDIA’s flagship model, the GeForce 8800GTX. In our first article regarding AMD Radeon HD 2900XT we chose to look closer at the card through the eyes of an enthusiast, partly because the drivers currently available aren’t the greatest but also because of the reported extremely high power consumption and heat dissipation of the R600 core.
A unnecessarily hot core is nothing you as a normal user would want, but as our overclocking expert Marcus ”Kinc” Hultin said in our Radeon HD 2900XT overclocking article, there are a few upsides with this for those who knows how to exploit this weakness.
Marcus ”Kinc” Hultin – ”You can’t have missed all the discussions about R600 being a real hottie. This is mainly due to the big leakage of the 80nm process, a similar problem to that Intel had with Prescott. Personally, from an overclocking point of view, I like hot hardware because it means that there is a good margin for overclocking if you’re able to remove the heat.”
For those who read our overclocking article it is no surprise that the R600 and Radeon HD 2900XT overclocks extremely well if the cooling is proper, but what we didn’t show is that the R600 chip is actually so hot that even the most extreme cooling is conquered.
With a cascade cooler on the Radeon HD 2900XT we reached a stable clock frequency of 1150MHz on the core which rendered in a new world record in 3DMark 05 with a single card, among others. Despite these extreme frequencies and the equally extreme performance, Kinc felt that there was more to come in the R600 core and even if the feeling he had might have been justified, those last MHz weren’t exactly easy to squeeze out.
Radeon HD 2900XT rigged for liquid nitrogen
Yesterday, it was time for some real overclocking, namely liquid nitrogen with a boiling point of around -196°C. A pretty big increase from the maximum -90°C a cascade cooler can offer. By attaching a solid copper container (solid GPU mousepot) on the graphics card’s core and by filling the container with liquid nitrogen you can easily push down the temperatures of even the most extremely hot graphics cards, which renders in even higher clock frequencies.
That’s exactly what Kinc did with the Radeon HD 2900XT and with the extra cooling the nitrogen provided a new top notch result was noted in core frequency, namely 1230MHz stable enough to run a round of 3DMark 03 which makes it the highest clocked graphics processor in the world so far. In order to reach this clock frequency a raise in core voltage was needed and when fed 1.53V the R600 put off a never before seen performance with a high-end graphics card. The card would namely have had managed even higher clock frequencies if it wouldn’t have been for the heat; it was too hot! As mentioned, we were using a solid copper container filled with liquid nitrogen with a boiling point of -196°C and yet this wasn’t enough to cool the R600 beast. At idle the copper container’s temperature rose from -90°C to around -70°C which made it impossible to push the frequencies any further.
During the past years, we have shown off lots of overclocking results where liquid nitrogen has been the last resort, one that has always pushed those cores to their absolute limits on both graphics cards and processors. We have pushed NVIDIA’s G80 architecture beyond 1GHz with liquid nitrogen and then the core itself simply reached it’s frequency limit, never before have we experienced that the cooling hasn’t been sufficient.
The fact that R600 undoubtedly at extreme conditions is too hot even for liquid nitrogen clearly shows why AMD chose to postpone the more extreme version of the Radeon HD 2900 series. The chip itself is very power hungry, but the power leaks in the 80nm processor are undoubtedly the reason for these extreme power consumptions and the even more extreme heat dissipation. This in itself is no good news for AMD, but we could look at it from the bright side as well.
AMD has a thoroughly promising graphics processor and our tests indicate that the power leaks in the 80nm processor might be even bigger than anticipated. With this in mind, if AMD does a good job with its 65nm process, as rumored, it has shedloads to accomplish with the R600 core.
Air-cooled processor and R600 at 1211/2000MHz
The fact is that we are looking at a 80nm graphics core that leaks power like no other but despite this it has no problems reaching higher frequencies with the right cooling. At 1211MHz which is the highest frequency we have proof of, the Radeon HD 2900XT performs an unbelievable 777GFlops (470GFlops at standard frequencies) which could be compared to around 40-50GFlops on todays quad-core CPUs.
Power consumption and heat dissipation with the R600 core is undoubtedly going to be debated and tested, which means that this naturally isn’t the last thing you are going to read on this topic. But the good thing is, you don’t have to be a rocket scientist to understand how much time AMD is currently spending on developing their 65nm version of its Radeon HD 2900XT.
For those who want to read more about the Radeon HD 2900XT and especially its overclocking potential in particular might want to check our ASUS HD 2900XT: Overclocking article.
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