Making the most of S3 - two S27 video cards in the MultiChrome mode

By:Dmitry Sofronov
Vladimir Romanchenko

I must admit, while publishing our November material on the then prepared mass production of graphic cards built on the base of Chrome S25 and S27 chips made by S3 Graphics and describing the preliminary data on these novelties, we, following the established practice, cast some doubts whether the varied boxes with these card would reach the lab. Since the time when only two companies survived on the field of the manufacture of chips for modern 3D graphics aimed at desktop PCs, there have been numerous attempts to enter the "club". They normally ended up in "on-paper" announcements or prototype chips, or, like in the case of XGI Volari Duo, release of quite limited quantities of retail cards.

As time has proved, this time the doubts cast upon the capabilities of S3 Graphics turned out to be in vain. This review and test run on a test bench assembled of S3 S27 video cards voluntarily purchased in the US retail are all a proof of that. Moreover, having presented its MultiChrome technology, from the very start the company lifted its arm against the class of SLI/CrossFire solutions, that is, systems with two graphic cards and honestly aligned promises with the reality. Moreover, already during CeBIT 2006 in Hannover VIA Technologies, the owner of S3 Graphics, demonstrated quite a number of samples of video cards built on S3 Chrome chips, and perhaps, more importantly, announced an impressive list of partners for the manufacture and sales of such cards.

As practice shows, it's just the final stage when novelties are sent to the retail in mass quantities proved fatal for many excellent companies with revolutionary ideas. Well, fortunately, not this time. Currently, video cards built on S27 chips already sell by retail on the US market. At the same time, we note that they sell under the company's own brand name - S3 Graphics.

Among VIA's partners willing to open up other markets are companies like MSI, Axper (Gigabyte's daughter structure), Digicool, Onda, Yeston , and other, less known. As official representatives of VIA disclosed during CeBIT 2006, most of the available partners intend to ship S3 Chrome series video cards to China, but currently an expansion to the European market is on the way.

In a word, it seems like the marketing side is well thought out and this time VIA / S3 Graphics have got a real chance to come back to the market of 3D graphics and strengthen own positions on it. Our today's material is to find out in what extent the strengthening will be.

Architecture and technologies

While announcing the line of Chrome20 graphic chips which currently includes two graphic processors- Chrome S27 and Chrome S25 (or simply S27 and S25), S3 Graphics from the very start did not promise the moon or extreme performance results. S27 and S25 are being positioned by the company as solutions aimed at the mid-end and low-end sectors of the market of modern graphics, respectively. Especially, from the very beginning the following was known: S25 and S27 support only the Shader Model 2.0+, and no support for SM3.0 will be implemented in them.

Was there originally a marketing sense in advancing with video cards that offered performance at the level of GeForce 6600 or Radeon X1600XT? It seems there was a sense, and for several reasons at a time. First, at least for the sake of finally becoming a real player on the market of 3D graphics, in any segment, so that to move forwards afterwards. Secondly, correct price positioning of cards of these pricing ranges, the most popular, will let S3 earn more to further improve the architecture.

And finally a complete set of auxiliary features. Even without a peak performance in 3D games, video cards built on Chrome S27 and Chrome S25 chips are equipped with a complete "gentleman's pack" of technologies including those used in modern "digital homes" - this argument coupled with the price is among the decisive today in choosing the items for new platforms by the system integrator. Combination of all these factors plus use of Fujitsu's 90-nm process technology in the manufacture with low-k dielectrics and without lead - all these have made it possible to create universal 3D chips with the good "performance per watt" index.

DirectX 9.0 graphic cores of the S3 Graphics Chrome S20 series offer four vertex and eight pixel processors of declared performance up to 5.6 bln pixel instructions per second, with 128-bit (4xFP32) precision for vertex operations and 96-bit (4xFP24) precision for pixel operations. Up to 16 parallel texture mapping passes are processed, there is support for 16x anisotropic filtering, volumetric and cubic texturing, programmable pixel-wise gamma correction, optimized read-write Z-buffer and many other modern technologies.

The core architecture that inherited the generic developments from the previous generation of GammaChrome, along with the full-featured support for DirectX 9.0 has been enriched with a number of modern process improvements. Among them is primarily the native support for the PCI Express bus in any of its version – from PCI Express 1x to 16x, which allows using S3 Graphics Chrome S20 series chips in video cards for a wide spectrum of applications.

Another key acquisition of the new core is a flexible universal memory controller that supports any types of the graphic memory - GDDR1, GDDR2, and GDDR3, which also imparts substantial flexibility in creating a wide spectrum of video cards with varied "price/performance" combination. The Chrome S27 chip supports the 32/64/128-bit memory bus, 32/64/128/256 MB of GDDR1/GDDR3 memory or 32/64/128/256/512 MB of GDDR2 memory, and the peak performance of the controller using GDDR3 memory reaches 22.4 GB/s (at the clock speed 700 MHz).

Finally, it is the S3 Graphics MultiChrome technology presented for the first time in S3 Graphics Chrome S27 series cards, which allows building the performance of a graphic system due to plugging in a second video card. In so doing, neither additional cables nor jumpers, nor special versions of cards on the base of Chrome S27 are needed, since the MultiChrome technology is supported by each of them by default – it suffices only a motherboard with matching PCI Express slots. In the MultiChrome mode, cards built on the base of S27 chips support two rendering modes - the Alternate Frame Rendering (AFR) in which each chip processes even/odd frames, and the Split Frame Rendering (SFR) in which each chip is in charge of processing its own (upper or lower) part of the frame.

Systems with two Chrome S27 video cards support resolutions up to 2048 x 1536 @ 75 Hz. Coupled with support for the HDMI interface the Chromotion 3.0 - full-featured output HDTV modes - up to 1080p, including the 16:9 format, hardware processing of MPEG-2 and WMV-HD, we get quite a balanced graphic subsystem for a second-rate PC.

The economical enough operation of Chrome S20 series chips is provided due to support for the S3 Graphics Power Wise, which provides a precise control over the power consumption, as well as due to the optimized design. At the same time, the number of transistors in the chips of S3 Graphics Chrome S20 series does not exceed 70 mln. It's just that coupled with the modern 90-nm Fujitsu process technology which allowed raising the clock speed of S3 Graphics Chrome S27 chips to 700 MHz (mClk700 MHz), which is higher than in any other modern mass-produced 3D chips for desktop PCs.

As regards low-end S3 Graphics Chrome S25 graphic processors, they are also used to produce video cards of the PCI Express õ16, x8, x4 and x1 bus, which will let achieve the clock speed of the core as high as 600 MHz and even more (mClk 400 MHz). The memory bus in S25 can be configured as 32-bit, 64-bit and 128-bit, at the same time there is support for up to 128 MB of DDR1, DDR2 memory, or the AcceleRAM Technology which is similar to the turbo technologies by ATI and NVIDIA, when additionally to the available onboard memory a distributed system memory - up to 128 MB in the 32-bit mode - is used.

The S3 Graphics Chrome S27 series offers the new video engine Chromotion Video Engine 3.0 which supports the vast majority of modern video standards and codecs, including Windows Media Video 9 (WMV9), MPEG-2 and MPEG-4, and is fully compatible to Microsoft DirectX-VA.

Owing to the HDTV Hi-Def technology, there is support for all the 18 ATSC DTV standards, including the 1080p. The chips offer support for the component (YPbPr) output, 4:4:4 transformation with 10-bit resolutions of the DAC, S-video and composite TV-outs in NTSC/PAL, 10-bit 400 MHz CRT DAC, ChromoColor technologies for a wide spectrum of color space transformations. In general, S3 Graphics Chrome S27 video cards support displays of resolutions up to 2048 x 1536 QXGA (3.1 mln pixels), as well as output to two monitors (HDTV/CRT, DVI/CRT, TV/CRT, or LVDS/CRT).

Let's sum up the brief research into the potential capabilities of S3 Graphics Chrome S20 series chips inherent to the architecture. No doubt, today you can't surprise with four vertex and eight pixel processors, and it is far not the fact that the clock speed 700 MHz will help make use of performance of these chips. On the other hand, the S3 Graphics Chrome S20 series chips offer a flexible enough memory interface, which coupled with the modern HDTV Chromotion 3.0 video engine allows this generation of 3D graphics by S3 to pretend for a certain place in the sun. To talk about some potential shares of the market, let's first take a look what these chips are capable of while running test and real gaming applications.

S3 Chrome S27

Now let's see what the top-end S3's video card Chrome S27 looks live. We received the video card to our lab just in the very option it is available on sale (in the US retail, of course).

The appearance of the front side of the box is strict and concise. It has a black background, a "S3 Graphics" logo, and a list of major advantages of the video card.

The reverse side of the box contains a more detailed description of the video card's features, with a substantial part devoted to the HDTV support and Chromotion Video Engine features - hardware engine embedded into the chip which improves the video playback quality.

The package bundle is rather modest - a drivers CD, a HDTV-out cable, a DVI/D-Sub adapter, and a small leaflet on video card's installation - a Quick Installation Guide.

The video differs in compact size, and half of the PCB is closed with a radiator of formidable dimensions, with a heat pipe running over to the reverse side of the PCB.

As was expected, on the reverse side of the video card there is the second half of the radiator.

To facilitate understanding of the cooler's design, let's bring in its photo taken when dismantled. As is seen from the photo, the heat pipe is positioned in a semicircular depression of the radiator and is closed on top with an aluminum lid. A similar structure is used also in the second half of the radiator. When installing on top of the video card, the radiators are fastened to one another with screws via reach-through holes in the PCB.

As is usual, the most interesting is hidden under the radiator. On the front side of the PCB we see a video chip and 4 memory chips. The semitransparent silicone drops act as restricting poles used to prevent splitting of the GPU chip on installing a radiator.

On the reverse side under the radiator, there are contact pads for 4 additional memory chips, that is, it is possible that video card versions with doubled memory capacity may emerge.

The core of the video chip is amazing for its tiny size. On the other hand, it is no wonder because the chip is made following the 90-nm process technology and contains a relative small number of functional blocks. The nominal operating frequency of the core is 700 MHz, which is an absolute record for video cards to date (for frequencies set by video card manufacturers). However, even 700 MHz for the core is not yet a limit. We'll be talking about the overclocking a bit later.

The video card uses 256 MB of DDR3 video memory assembled of 4 Samsung chips of 1.4 ns access time, which is equivalent to 1400 MHz operating frequency. That is the frequency the memory runs by default. As was mentioned earlier, the PCB used allows easily doubling the video memory capacity to 512 MB whenever necessary.

At that, we stop introducing to the exterior of Chrome S27 and move on to the tests.

Overclocking

The nominal frequencies of Chrome S27 are 700/1400 MHz for the GPU/memory, respectively. But that is not yet a limit. Due to the good-quality cooling system, we were able to overclock the VPU to 875 MHz! Unfortunately, the card failed to overcome 900 MHz, and upon loading 3DMark'05 there were blurs and artifacts on the screen. We were able to overclock the video memory to 1600 MHz mainly due to using Samsung chips. Therefore, the total GPU overclock proved as high as 25%, and 14% for the video memory.

Preliminary Notes

Prior to getting familiarized with the test results, we should make some important remarks. Unfortunately, for quite a long time S3 video drivers have left much to be desired. In the tests, we used the latest drivers available on the web site of S3 Graphics - version 15.18.05l dated 12 April 2006. Below you can see a tab to adjust the driver settings for Direct3D applications

As you can see, the pack of settings available to adjust is not that wide.

This is a tab to adjust the driver settings for OpenGL applications. Here, a list of settings is fitted within 3 lines. Interestingly, there is an option to enable the anisotropic filtering (up to AF16x), but you won't be able to enable anti-aliasing for OpenGL applications.

We ran the tests just with the settings shown on the screen shots. That is, without the FSAA and AF enabled. Our attempt to enable FSAA in Direct3D resulted in a catastrophic drop of performance - as many as 6 times for Half-Life2. Nor the attempt to enable anti-aliasing manually in DOOM3 helped either. There was no drop in performance, nor there was any change in the image quality. The most probable cause of such behavior of Chrome S27 is just in the demanding modes - presumably, in the drivers. Engineers at S3 Graphics definitely have something to work at, although much has been done so far. In the NO AA/AF mode, the video card was running stably, without any artifacts. So, while engineers at S3 Graphics are conjuring about performance in the demanding graphics modes, we decided to test the video card in the NO AA/AF mode.

Benchmarking

Here are participants of today's tests:

• S3 Graphics Chrome S27 - 8 pixel pipelines, 4 vertex pipelines, nominal frequencies - 700/1400 MHz.
• S3 Graphics Chrome S27 - 8 pixel pipelines, 4 vertex pipelines, frequencies after overclocking - 875/1600 MHz.
• GeForce 6600 with DDR2 video memory - number of pipelines 8/3, frequencies 350/800 MHz
• Radeon X1300Pro - 4/2 pipelines, frequencies 600/800 MHz
• Radeon X1600XT - 12/5 pipelines, frequencies 590/1380 MHz

Such a selection of rivals may seem somehow strange. Indeed, on the date of writing the review the price of Chrome S27 was 99$, according to US large online shop www.newegg.com. At the same time, X1600XT costs about 150$, and X1300Pro - about 80$. Of course, in terms of price it would be more appropriate to choose X1600Pro for comparison, but it was not available at the time of running the tests. Of the video cards reviewed today, the closest to Chrome S27 in terms of price is the GeForce 6600 DDR2. Its price is just at about 100$.

Anyway, we did use just these cards for comparison. The performance of Chrome S27 quite strongly varies with application, so we selected such a vast range of comparison. Now let's look at the test results.

For tests we used NVIDIA 84.21 WHQL, ATI CATALYST 6.4, and S3 Graphics 15.18.05l (04/12/2006) drivers.

The results produced for ATI video cards are presented in bright red, for NVIDIA - in green, and Chrome S27 - in yellow. The values in brackets stand for the nominal frequencies, and those with the character @ - for results produced after overclocking.

As we expected, at 3DMark'05 the video cards ranked as per the speed of executing shaders. Of course, Radeon X1600XT which along with high frequencies has 12 pipelines takes a lead at this test. Then, Chrome S27 follows. There was an unpleasant surprise for us to see that the result produced through overclocking Chrome S27 is merely 5% although the GPU frequency was boosted by 25%, which mainly determines the result at 3DMark'05, let alone the 15% memory overclock.

At 3DÌark'03, the results for Chrome S27, albeit slightly, but take a lead over those for GeForce 6600 DDR2 and X1300Pro. Judging by the results of synthetic tests, we can assume that it will be rather hard for Chrome S27 to hold its grounds even in center of the middle-end range in the sense it is currently understood by the main players on the market, i.e. ATI and NVIDIA. This is especially true because the low-end presented by X1300Pro is not so distant.

Now let's see what Chrome S27 is worth of in real games.

That's a surprise, isn't it?! Despite the very high clock speeds and greater number of pipelines, Chrome S27 loses at Half-Life 2 to all the rivals, including the low-end X1300Pro. Even overclocking can't help. It seems like pipelines are different.

At DOOM3, the situation is somehow better. Chrome S27 is very close behind X1600XT and shows quite decent FPS up to 1280õ1024 inclusive. Since S3 Graphics had problems with OpenGL drivers for quite a long time, the produced result can be called simply fantastic. Such a radical improvement just at DOOM3 suggested the idea - "aren't there any optimizations just for this game?". To verify this hypothesis, we renamed the file doom3.exe and ran the integrated test demo1 once again. In the end, at 1024õ768 after renaming the file we got not 55 FPS but merely 44. That is, there is optimization just for DOOM3, but the OpenGL driver from S3 is quite on par either.

Since F.E.A.R. makes quite intensive use of shaders and Chrome S27 offers high clock speeds enough to execute shaders fast (judging by the 3DMark'05), we could expect that at this game Chrome S27 would show good results. But.. it didn't work. The results for Chrome S27 and GeForce 6600 DDR2 are practically equal, despite the twofold superiority of Chrome S27 at frequencies.

Final Words

Chrome S27 leaves a dual impression. On the one hand, it offers a low price, good manufacturing quality, good cooling system, high clock speeds and decent enough speed of shader execution, which gives hopes for good performance in modern games. On the other hand, we could observe an inefficient scaling of performance over the frequency, which is a sign of imperfection of the internal architecture, or - imperfection of drivers (I would "prefer" the second option, since there is still hope that after the driver improvement the high clock speeds of Chrome S27 might show their worth). Another shortcoming of Chrome S27 is more likely potential - that is, support for Shader Model of merely version 2.0.

We still have time to fight!

Nevertheless, we should admit that despite all of its shortcomings, Chrome S27 is quite an efficient product, although it can't pretend for high-end despite its top ranking in the product line. Not quite a long time ago, it seemed that S3 Graphics would no longer be able to produce something really working. Our high respects to the company's engineers. We appreciate their hard work and perseverance. The most interesting is that engineers at S3 Graphics decided not only to stop "sitting idle" but also presented their own technology for merging performance of two video cards, named the MultiChrome. You will know what it is and how it works on the next page.

S3 Graphics has not only produced a full-fledged product but also presented its own technology for merging performance of two video cards, named the MultiChrome. As is easy to guess, the prefix "Multi" just implies the possibility of joint operation for several merged video cards. For now, we can state with absolute confidence that at least two video cards can be operated in the MultiChrome mode. The matter of consolidating performance of more than two video cards by S3 Graphics is still open, but in my view there aren't any obstacles for that. Let me explain why.

Engineers at S3 Graphics addressed the task of consolidating performance of two video cards pragmatically (in the good sense of that). All what is needed to produce the MultiChrome mode from two Chrome series video cards is two onboard PCI-E slots running at the same speed, that is, in the symmetrical mode. Of course, since S3 Graphics is a subsidiary of VIA, it is recommended to use the MultiChrome mode on motherboards built on the VIA K8T900 chipset. As we had already the chance to make sure - those who will follows this recommendation will not lose in 3D performance at all. Owners of other motherboards that support PCI-E slots in the symmetrical mode don't have to rush about either. The MultiChrome works fine with other chipsets and without any tricks like modified drivers. For instance, on our test bench where ASUS A8N-SLI Deluxe is used, the MultiChrome mode was enabled without problems and the test results didn't make any difference from those produced with VIA K8T900. Once again, S3 Graphics has proved our surmise that video cards don't have to use the native chipset to be able to operate in the mode of merged performance. Who knows whether such simplicity to chipsets will stay on from S3 Graphics if the company will ever take a position on par with ATI and NVIDIA. Time will tell. But for now let's take a closer look into MultiChrome on our customary test bench

As I already stated, to enable the MultiChrome mode, the PCI-Express slots should be first switched to the symmetrical mode. In our test bench that means switching from 16+1 to 8+8. That done and video drivers installed, on the S3Config3D tab there appears the "MultiChrome" option together with the possibility to select options for OpenGL and Direct3D.

Then, to enable the MultiChrome mode, it suffices to select the "Enable MultiChrome" option and press the "Apply" button. After that, a message asking to confirm enabling the option will be displayed. We press "Yes" and get the MultiChrome up and running. On the screenshot, you can see options selectable for the MultiChrome mode. Unfortunately the option of selecting the rendering turned out to be disabled. Therefore, we were unable to forcedly select a certain frame rendering mode - AFR or SFR - and had to rely upon the driver's intelligence in choosing the most suitable mode automatically. These are the conditions in which we were running the tests. As regards the full-screen anti-aliasing and anisotropic filtering, this time as well we decided not to enable these options due to the same reasons as described for testing a single Chrome S27 video card.

We used S3 Graphics drivers of version 15.18.05l (dated April 12, 2006)

Below are the results for testing two Chrome S27 video cards in the MultiChrome S27 mode as compared to the same but single video card. The video cards were running at the nominal frequencies.

3DMark

Half-Life 2

DOOM3

F.E.A.R.

As you can seem the boost gained through merging two Chrome S27 video cards is there and quite substantial. In order to give a better estimate of the relative boost, we are bringing in an assembled diagram in which the performance boost percentage gained due to MultiChrome as compared to that of a single video card.

Well, we have never seen that before. The 88.5% performance boost is really something unheard of! Of course, 3DMark'05 is synthetics where everything is possible, but the figure is anyway impressive indeed. In real applications, the performance boost proved somehow lower, but also on par. However, there were some surprises. We saw no performance boost in Half-Life 2. Interestingly, the video card usage indicator which can be enabled on the S3Config3D tab showed that in Half-Life 2 only one card was operating. So the results don't make difference from those for a single video card. I presume it is related to incorrect behavior of the video driver which did not decide which rendering mode to choose. Perhaps, with the manual rendering mode selected we would have produced a different pattern of results. However, this feature is still disabled in the drivers.

Summary

On the whole, despite some flaws, we must admit that MultiChrome is a real working technology that demonstrates a superb result! What is especially interesting is that even in the MultiChrome section at the official web site of S3 Graphics there are figured which prove lower than those which we produced during the tests. Indeed, this modesty is worth of imitation.

As was expected, the S3 Graphics Chrome S20 series chips do not pretend for the title of a new king of 3D graphics market. At the same time, it offers a sufficient set of characteristics to become quite an everyday thing as part of home-based and office systems, value "digital homes", whatever TV-boxes. By the way, I presume no one will be surprised to see that with the start of a mass production of VIA C7-M processors and S3 Graphics Chrome S25/S2 graphics, the VIA EDEN platform will acquire "the second wind" and will be able to take a place of more dignity.

Finally, a few of words on the future prospects. Presumably, engineers at S3 Graphics are already busy developing a new generation of their 3D processors. There is every reason to assume that the high enough potentials inherent to the current generation of chips, namely, in the possibility of support for clock speeds as high as 700 MHz and even more, in the flexible memory interface, in the modern HDTV Chromotion 3.0 video engine will let S3 Graphics in future improve these advantages and claim of itself as an "equal inter pares" on the market of 3D graphics. Why not?