X-bit labs

ATI RADEON X800: R420 Totally Exposed (page 4)

Category: Video

by Tim Tscheblockov , Alexey Stepin , Anton Shilov

[ 05/04/2004 | 06:42 AM ]

As we have already mentioned, the power consumption and also the heat dissipation of the R420 chip is claimed to be not any higher than that of R360, that is why I believe the answer to this question will be positive.

Well, practical tests proved our point: the cooler did its job very well. It was not cold at all, but its temperature didn’t cause us any concerns.

Just like in case of the reference RADEON 9800 XT, there was barely any noise produced by the cooling system. Having sped up to the maximum rotation speed during boot-up, the cooler slowed down immediately and worked at half the speed. Only a few times the fan reacted to the VPU temperature growth and started rotating faster making a bit more noise in this case.

So, from the noise level point of view, new ATI Technologies’ solutions look much more attractive than the NVIDIA GeForce 6800 Ultra.

Since we had two graphics cards based on different RADEON X800 versions, we decided to remove the coolers from both of them to see, if there are any visual differences between the two graphics processors, and if there are any, then we should definitely try to find a way to unlock the 4 additional pipelines on RADEON X800 PRO.

However, when we removed the heatsinks, we discovered no differences between the chips. It looks like the info about the type and hence about the configuration of the pixel pipelines of the given graphics chip is written in the graphics card BIOS, or in the special Read-Only chip registers, i.e. it is not determined by the location of resistors on the die or on the graphics card PCB. So, here are a few close-ups for RADEON X800 XT and RADEON X800 PRO:

The marking suggests that one of the chips is manufactured on the 11^th week of this year, while the second chip – on week 13. So, they are hardly any newer than the NV40 chip, we had on our GeForce 6800 Ultra sample during the test session.

Both graphics cards are equipped with GDDR3 memory in Samsung chips. Each graphics card is equipped with 256MB of memory. However, RADEON X800 XT Platinum Edition boasts memory with 1.6ns access time, which can work at up to 600MHz (1200MHz DDR) frequency, while RADEON X800 PRO features slower memory with 2ns access time capable of working at the maximum of 500MHz (100MHz DDR).

The nominal graphics memory frequency of the RADEON X800 XT Platinum Edition is 560Mhz (1120MHz), while RADEON X800 PRO features the memory working at 450MHz (900MHz). As you may have noticed, both graphics cards have their memory working at slightly lower frequencies than the allowed maximum, probably for stability purposes.

It is also remarkable that the memory chips on our graphics cards were not equipped even with the simplest heatsinks. Of course, the heat dissipation of the GDDR3 memory is considerably lower than that of the GDDR2, but when the card is working at such higher frequencies, the memory chips definitely need additional cooling.

Since there was no extra cooling for the memory chips on RADEON X800 XT, they got scary hot when the memory bus workload increased, and we couldn’t even touch them without burning the fingertips. Moreover, after a while we noticed a few visual artifacts on the monitor, which are typical of memory over-overclocking. We immediately installed a 120mm fan blowing extra air along the graphics card, and this resolved the memory overheating issue completely.

Well, we can only hope that memory overheating is a problem of the samples we got for our tests, and the graphics card makers will keep it in mind and equip their mass products with memory cooling solutions.

So, the first impressions of the graphics cards appeared highly positive: the new RADEON X800 XT Platinum Edition and RADEON X800 PRO based graphics solutions look very nice against the background of NVIDIA GeForce 6800 Ultra, even despite a few drawbacks we discovered and pointed out to you.

Now it’s high time we paid more attention to the architecture of the new graphics processors from ATI.