A relatively fresh product, RADEON LE graphics cards, which started selling not so long ago, have captured the public attention and thus raised a lot of questions. The thing is that the standard version of these mysterious cards is almost similar to ATI RADEON SDR in terms of performance and price, but the new offsprings respond much better to the users' attempts to improve their "nominal" performance.

See yourself: RADEON LE is actually a common RADEON DDR 32MB, featuring a bit lower frequencies and disabled Hyper Z technology. If it weren't for these two points, the performance of this new card wouldn't be so much lower than that of a common RADEON DDR 32MB.

The mysterious thing about RADEON LE is that ATI has disavowed any connection with the launching of these graphics cards. In fact, this story doesn't seem to be entirely true. We dare surmise that RADEON LE stands for a batch of graphics cards that failed to be sold to some huge OEM companies. Perhaps, these cards with low core and memory frequencies were originally manufactured for some OEMs, but eventually they were not called for. To get rid of the "non-standard" cards, ATI decided to entrust them to one of its partners, so that they were finally sold at a lower price. At the same time, to prevent any rivalry with more expensive ATI RADEON DDR, the drivers of RADEON LE cards were deprived of Hyper Z - one of brand features of RADEON-based graphics cards.

The fruits of this decision will be scrutinized further. However, judging by the price of RADEON LE (some $90-100), these graphics cards are likely to become serious competitors to GeForce2 MX-based cards.

We have to stress that ATI is trying to explain the birth of its RADEON LE in a bit different way. According to the official RADEON LE FAQ, which you can find here:

RADEON LE is an entry level member of the RADEON family that is being offered specifically for the Chinese market by Althon Micro and AMI Technologies Corp, ATI strategic partners. Providing good performance at an aggressive price point, the RADEON LE benchmarks very well against the competition in this segment.

Although this story stands on ATI's official web-site, it can hardly be true because it doesn't sound logical at all. The major thing that disagrees with their statement is that RADEON LE is available worldwide and not just in the Asian market. Nevertheless, we don't think that it's worth caring about the origin of the notorious RADEON LE. Its performance investigation seems to be of greater interest to us.

There have already been many articles, dedicated to graphics cards by ATI (except for RADEON LE), so there is scarcely any need to describe the peculiarities of their architecture.

Nonetheless, it is worth mentioning that RADEON chips feature ATI's brand technology. We mean HyperZ

HyperZ Technology

The technology aims to reduce the workload falling upon the local memory bus bandwidth by optimizing the work of the z-buffer.

HyperZ technology is based on three algorithms:

• Hierarchical Z. This algorithm allows determining visibility of the pixel before it is displayed and makes the accelerator render it only if necessary. As a result, in case the scene has a big number of overlaid objects, the accelerator can be tangibly unloaded, since the pixels, eventually hidden by those that are closer to the observer, are not engaged in rendering. The algorithm is probably based on using a "lower resolution" Z-buffer, obtained when the frame is split into small rectangular sections. STM KYRO, for instance, has implemented a similar idea in its tile architecture.
• Z-Compression. This algorithm compresses the Z-buffer on the hardware level. Consequently, memory bus is partially unloaded and there is extra space for textures in the local memory of the accelerator.
• Fast Z-Clear. This algorithm helps to notably speed up clearing the z-buffer before every new frame is rendered.

These three patterns let the chip with only two pixel pipelines and four texturing units keep up with GeForce2 GTS in hard 32-bit modes, although GeForce2 boasts four pipelines, eight texturing units and higher core and memory frequencies.

Enough for theory, let us now see how good RADEON LE is, if compared to other cards of RADEON family and GeForce2 MX, which is the main rival to RADEON LE in price.

RADEON LE & RADEON DDR: who is who?

Now and then, dishonest and jackleg retailers tend to sell RADEON LE as a standard RADEON DDR, which is about $50 more expensive. So, let us first learn, how to tell RADEON LE from RADEON DDR, according to their looks.

ATI RADEON DDR		ATI RADEON LE

As you can figure out from the photos, only RADEON LE is equipped with a passive heatsink. Such heatsink is possible to install, because the nominal core frequency of RADEON LE is comparatively low. Nevertheless, RADEON LE cards feature the same chips as RADEON DDR.

The same situation takes place with the memory - both the cards have similar microchips onboard:

Apart from graphics core cooling matters, the graphics cards differ in marking, so look at the RADEON logo:

ATI RADEON DDR		ATI RADEON LE

Furthermore, the layout of RADEON DDR and RADEON LE is not identical in one certain place:

ATI RADEON DDR		ATI RADEON LE

Now that we have cleared out, how these two graphics cards differ in appearance, we are free to pass over the results of the tests.

Our Testbed

We made use of the following:

Testbed:

• Intel Pentium III 1000MHz CPU;
• ASUS CUSL2 i815e mainboard;
• 128MB PC133 with ECC memory;
• Western Digital AC36400-32LC 6.4GB HDD.

Graphics Cards:

• ATI RADEON DDR 32MB;
• ATI RADEON SDR 32MB;
• RADEON LE 32MB DDR;
• ASUS V7100 (GeForce2 MX).

Drivers:

• NVIDIA Detonator 6.31 forASUS GeForce2 MX;
• 4.13.7078 for RADEON LE / SDR / DDR.

Test applications:

• Quake III Arena;
• 3Dmark2000 Pro;
• Unreal Tournament;
• Mercedes Benz Truck Racing.

Utilities:

• RadeonTweaker 0.10.0;
• PowerStrip 3.0beta.

We tested inWindows98 SE and DirectX 8.0.

Drivers

The tested sample of RADEON LE was shipped with a heavily out-dated driver, so we had to download the latest driver version from ATI's site. It was 4.13.7078, intended for DirectX 8.

The driver set included an inf-file for all RADEON graphics cards. Strange as it might seem, it contained no information about RADEON LE, so the card was identified as RADEON DDR.

As far as clock rates are concerned, PowerStrip indicates that the core frequency of RADEON LE is lower than that of RADEON DDR and totals 148MHz. Later on, as we tried to overclock RADEON LE and RADEON DDR, it turned out that the top frequency for trouble-free work was about 190MHz for both cards. It proves that the chips, which are installed on RADEON LE are no fake ones and the lowered clock frequency of RADEON LE is nothing more than a marketing trick.

Another characteristic feature of RADEON LE is that by default it has disabled HyperZ in Direct3D. Although the content of the registry with HyperZ properties is practically the same for RADEON SDR/DDR and RADEON LE, the cards act differently. Namely, if the registry gives no settings concerning HyperZ, RADEON SDR/DDR work with enabled HyperZ in Direct3D, while RADEON LE has it disabled.

That's what this part of the registry looks like when the driver for RADEON SDR/DDR/LE is installed:

Apparently, the driver identifies the card by the version of BIOS and then either enables or disables HyperZ in Direst3D. However, if you set in the registry all the keys for HyperZ directly, then all RADEON graphics cards will obey the orders. :) So, it's quite enough to set HyperZ reg-patch for RADEON LE, or to enable HyperZ in Direct3D with the help of RadeonTweaker or PowerStrip.

Here is the discussed part of the registry when HyperZ in Direct3D is enabled:

When HyperZ in Direct3D is enabled, RADEON LE will work almost like RADEON DDR, except for the working frequencies and a few other things. The frequencies can be increased in PowerStrip, but the "other things" can be hardly changed. The matter is that even if the frequencies are brought up till the level of RADEON DDR and HyperZ is enabled, RADEON LE still performs a little bit worse than RADEON DDR. Obviously, it's a matter of the BIOS version, which is not the same for RADEON LE and RADEON DDR. We don't see any other reasons for this small lag.

Speaking about HyperZ in OpenGL, we can assure you that it is enabled by all RADEON graphics cards, including RADEON LE, even though in Direct3D HyperZ is disabled by RADEON LE cards.

If (merely as an experiment) you wish to disable HyperZ in OpenGL, you should use RadeonTweaker. Then you'll see the following item in the registry:

To make sure that HyperZ in OpenGL is enabled for RADEON LE, we simply tried to disable it. When HyperZ in OpenGL is disabled, all RADEON graphics cards, including RADEON LE, suffer a sharp performance drop, e.g. in Quake3 Arena the drop makes 15-20% no matter what resolution you set. Anyway, we won't disable HyperZ without real need, will we? :)

Well, we have paid due attention to the peculiarities of RADEON LE, now it is high time to turn to the results of our tests.

Performance

The results bring no surprise: the whole bunch of RADEON cards lags behind those based on GeForce2 MX in 16bit color mode and get their own back in 32bit. GeForce2 MX owes its victory to higher core frequency and to the general disadvantage of ATI's cards: poor performance in 16bit mode. And the laurels of RADEON cards were won only due to HyperZ technology. The test showed that RADEON LE with the working frequencies equal to those of RADEON DDR raced neck and neck with it. This fact proves our assumption about the enabled HyperZ in OpenGL for RADEON LE.

It is interesting that the results in 16bit and 32bit color modes look very much alike. In this game the overdraw is relatively small, so HyperZ gives almost no gain. The performance in the game mostly depends on the working frequencies and type of memory installed into the graphics card.

These results are somewhat boring. Well, there is nothing to do about Unreal Tournament ... In all resolutions but for 1280x1024x32 the performance was limited by the CPU, and at 1280x1024x32, as the cards' uneven behavior in this demo shows, the samples simply lacked local graphics memory, so they had to deal with the slower system memory.

Naturally, it's a synthetic test, but it's the only one, which clearly demonstrates a significant performance gain, achieved with enabled HyperZ on RADEON LE. There is a good deal of smart Direct3D games with a rather large overdraw that are able to reveal the advantages of HyperZ, but none of them boasts an integrated benchmark. This way, in games of the kind we can only rely on 3Dmark 2000 to estimate the performance of RADEON LE compared with other graphics cards.

We seem to have commented on all the obtained results. Let us sum it all up now.

Conclusion

RADEON LE, a cheaper version of the regular RADEON DDR, has turned out pretty competitive. With some minimal improvements introduced (we mean enabled HyperZ in Direct3D and overclocking up to the level of RADEON DDR), the new card keeps up with its elder brother and overtakes its closest rival, GeForce2 MX, in 32bit color mode. ATI's recent drivers have also become notably better.

Finally, RADEON LE is sure to rock the positions of GeForce2 MX in the Low-End sector, unless RADEON LE is a contingent product and ATI gives up manufacturing it in future (even via Chinese manufacturers).