There is not so much time left until the DDR systems start selling in mass. In the beginning of next year after a number of delays caused by engineering and manufacturing problems, we should finally be able to buy in retail ALi MAGiK 1 and AMD-760 based mainboards for AMD Athlon CPUs and VIA Apollo Pro266 based mainboards for Intel CPUs. Besides, AMD is also planning to start shipping its new Athlon processors supporting 266MHz FSB. That is why the growing interest towards DDR systems is quite understandable. Certainly, the greatest interest is expressed towards AMD DDR platforms, because the use of DDR memory in these platforms promises to be highly efficient and is expected to provide a considerable performance boost. As a result, the competition in the CPU market will get harder.

We have already discussed the advantages of AMD Athlon CPUs combined with the DDR memory in our Iwill KA266-R Review and Review of AMD Athlon 1.2GHz with 266MHz FSB. The benchmarks in both articles showed that that the use of DDR SDRAM guaranteed a 10% performance gain on the average. However, we should bear in mind that all the tests carried out for these investigations were run on one and the same DDR mainboard based on ALi MAGiK 1 chipset. Nevertheless, there is one more chipset introduced by AMD in order to push forward the new CPUs and DDR technology: AMD-760. Even though the mainboards based on this chipset will turn up a bit later than those on the chipset from ALi, AMD-760 is expected to provide higher stability and performance, because it was worked out by the CPU developers directly. That's why testing Athlon systems with a mainboard based on AMD-760 is of great interest to all of us.

There are about a dozen of mainboard manufacturers who have already announced their products on AMD-760. However, only one board is expected to be the first to appear in the market: Gigabyte GA-7DX. In fact, in Japan you can now buy a modification of this mainboard, GA-7DXC, which supports PC1600 DDR SDRAM and only those Athlon CPUs featuring 200MHz FSB. As for the fully-fledged mainboard versions, they aren't available yet. We were lucky to get a sample of Gigabyte GA-7DX mainboard supporting PC2100 DDR SDRAM and 266MHz FSB. So, this interesting piece will be the topic of our today's review.

Chipset

AMD isn't a real chipset developer in the full meaning of this word, because this market sector isn't the company's major. However, it is impossible to sell CPUs without proper chipsets supporting them. That is why AMD develops and manufactures a limited amount of chipsets, which could help push forward its processors. This allows the company to avoid a lot of trouble when the chipset makers delay their products and makes the company independent of the chipset industry in a way. If you remember, when AMD introduced its first Athlon CPUs they also offered the mainboard manufacturers AMD-750 chipsets supporting them, and then a bit later AMD-750 was replaced by VIA KX133.

Now it's high time AMD said its word in the chipset market again. Cut-throat competition with Intel Pentium 4 CPU forced AMD to think of some ways to speed up its own processors. The company found a way-out and starting from 1January, 2001 AMD will begin shipping new Athlon CPUs with 266MHz FSB. However, the faster processor bus with the bandwidth 33% higher required faster memory bus as well, because the bandwidth provided by PC133 SDRAM appeared twice as low as that of the new processor bus. So, the system memory was about to become the major bottleneck of the system that's why AMD decided to turn to DDR memory, since it could help solve the problem.

To make the transition to a new FSB and a new memory standard easier, AMD introduced AMD-760 chipset. We should point out that AMD did the right thing, because the chipset manufacturers who had promised to introduce DDR SDRAM and new FSB support in their products failed to prepare to start mass shipments in the beginning of 2001.

AMD-760 chipset features traditional architecture and consists of two chips: AMD-761 North Bridge and AMD-766 South Bridge. The bridges are connected with each other via the PCI bus. In other words, AMD didn't work out any new special buses for this purpose, unlike VIA, for instance, which introduced a new V-Link bus for its DDR chipsets.

AMD-761 North Bridge supports EV6 bus working at both: 266MHz as well as 200MHz. The chipset also allows using both types of memory: PC1600 DDR SDRAM or PC2100 DDR SDRAM. That' why the mainboard based on AMD-760 chipset may work with new AMD Athlon CPUs with 266MHz FSB as well as with the today's Athlon and Duron processors supporting only 200MHz front side bus. However, unlike the other DDR chipset for AMD processors, ALi MAGiK 1, AMD-760 features a synchronous memory bus. It means that in case the CPU works with 200MHz FSB, the memory will always operate at 200MHz too and provide the bandwidth of 1.6GB/sec. Faster PC2100 DDR SDRAM can be used with AMD-760 in nominal mode only if the CPU supports 266MHz bus frequency.

However, unlike ALi MAGiK 1, the AMD chipset supports up to 8 memory banks, which means that there may be up to 4GB of DDR memory used in the system. The only thing you should remember if you decide to use so much memory: in case of over 2 memory modules all of them should be registered memory modules (with extra buffers). So, with the regular memory modules installed, you will be able to have 2GB at the maximum. Besides, the memory controller integrated into AMD-760 also supports ECC.

Of course, the system controller of AMD-761 has pretty standard features: it supports AGP 4x and up to 7 PCI devices.

As far as the South Bridge - AMD-766 - goes, it has been hardly changed since the times of AMD-750. Although it acquired ATA/100 support and allows connecting up to 4 USB devices, it doesn't have some of the functions, which you may see in other contemporary South Bridges. First of all we would like to point out the absence of AC'97 link, which means that the mainboards equipped with AMD-766 South Bridge won't support AC'97 software sound and AMR/ACR/CNR slots.

Therefore, most companies manufacturing mainboards based on AMD-760 chipset prefer VIA 686B to AMD-766 and usually replace the latter with the South Bridge from VIA. Especially since the PCI bus used in AMD-760 chipset to connect the Bridges allows a replacement like that. The only thing needed is the corresponding support in the mainboard BIOS and that's it. With VIA 686B chip the mainboard manufacturers get not just AC'97 sound but also "free" hardware monitoring, which controller is integrated into VIA South Bridge.

The table below shows the major features of AMD-760 chipset compared to its competitors:

Closer Look

After we studied carefully the peculiarities of the chipset used in Gigabyte GA-7DX mainboard, let's pass over to the board itself. First come the specifications:

Well, now that we have already got acquainted with the features of the chipset used in Gigabyte GA-7DX, let's pass over to the mainboard we got for review. First let's take a closer look at the official specifications of the product:

Like in case of AMD-750 chipset, Gigabyte again worked side by side with AMD when developing their new AMD-760. That's why no wonder that Gigabyte GA-7DX appeared the first mainboard on AMD-760 chipset to turn up in retail in the very beginning of the next year. This event could have happened much earlier, if it hadn't been for the problems discovered in AMD-760 chipset working with PC2100 DDR SDRAM. As a result, Gigabyte GA-7DXC mainboard version came out. It supported only those CPUs with 200MHz FSB and PC1600 DDR SDRAM. This mainboard is already available in a number of Japanese hardware stores.

Being the second DDR mainboard after Iwill KA266-R, Gigabyte GA-7DX features 2 184-pin DIMM slots for this memory type. Gigabyte decided not to deal with the Registered DIMM support, that's why the mainboard doesn't physically allow installing over 2 DIMM modules. Nevertheless, two slots are most likely to be just enough, especially bearing in mind that 1GB PC2100 DDR modules should become available in the near future already.

Unfortunately, AMD-760 chipset doesn't allow clocking the memory bus and the processor bus asynchronously. As a result, Gigabyte GA-7DX can reach the top of its potential performance only if the new AMD Athlon CPU with 266MHz FSB is used. Although these CPUs aren't selling yet, AMD promises to make them available in January. In case of the regular Athlon or Duron CPUs supporting 200MHz FSB, the memory is also clocked only for 200MHz and the performance of a system like that turns out hardly much higher than that of a system with the ordinary PC133 SDRAM.

Socket A on Gigabyte GA-7DX is nearly pressed to the chipset North Bridge. However, the developers in some mysterious way managed to put two capacitors between them. These elements are most likely to prevent you from equipping your CPU with a massive cooler, such as Chrome Orb or Super Orb.

Gigabyte GA-7DX is equipped with a universal AGP slot, which allows using both: 1.5V graphics cards as well as 3.3V AGP 2x and 4x graphics cards. This slot features a special retention mechanism, which holds the cards in the correct position. Although AGP slot is placed very close to DIMM slots, the graphics cards installed into this slot will never block the DIMM clips, so no need to worry. Moreover, there are 5 PCI and 1 AMR slot used for low-cost software modems and sound cards, which is very valuable for OEMs. All the PCI slots support full-size expansion cards. As for ISA slots, there are none of them on GA-7DX: Gigabyte seems to consider them too out-dated already…

The size of GA-7DX is quite standard for the today's ATX mainboard. That's why there shouldn't be any problems when installing it into most PC cases. However, the ATX power supply connector isn't located in the best place, between Socket A and the ports on the mainboard rear edge. As a result, the ATX power cable will go right above the CPU, hindering air circulation and proper processor cooling.

However, IDE and FDD connectors were put exactly according to the ATX specification: in front of the DIMM slots. So, IDE and FDD cables will not be in the way in the assembled system. As for the additional connector for one more pair of USB-ports, it is situated on the mainboard left edge. That's why if you decided to have 2 USB ports more, you would have to install the bracket with the Outs (which isn't included into the package, by the way) into the very last bay on the case rear panel.

As usual, Gigabyte provided its GA-7DX mainboard with hardware PCI sound controller - Creative CT5880. The interesting peculiarity of the sound realization is the use of Sigmatel STAC9708T four-channel codec. From the practical viewpoint it means that the integrated sound card on GA-7DX is also four-channel and allows connecting one more pair of speakers to the Line-In.

For the South Bridge Gigabyte selected VIA 686B, which ensures ATA/100 support. It has become very popular recently to make the first IDE connector red, which indicates that the mainboard supports ATA/100. So, did Gigabyte.

However, this is not the only advantage of this South Bridge. This chip is also responsible for hardware monitoring. The mainboard is equipped with 2 thermal diodes. The information about the CPU temperature is taken from the diode located in the middle of Socket A that's why it is not quite adequate. The chip also monitors 4 voltages and the rotation speeds of 2 coolers, though there are 3 cooler connectors altogether on GA-7DX.

As for the mainboard BIOS, GA-7DX uses Award Modular 6.00PG with a pretty standard settings list. In order to simplify the work with the BIOS, Gigabyte noticeably reduced the amount of settings accessible for modification via BIOS Setup. Nevertheless, all the major settings, including memory timings configuring, remained.

Gigabyte GA-7DX North Bridge is equipped with an active cooler. There is a regular heatsink and a fan like those, which you may see on the graphics cards. It's hard to say whether it tells on the mainboard stability that greatly, however, Gigabyte isn't the only one to resort to this kind of cooling solution. Active cooling will be also used on the upcoming AMD-760 based mainboards from ASUS and ABIT.

Also GA-7DX features a piezo beeper, which stands for the PC-speaker, and a tiny yellow LED indicating when the DIMM slots are powered.

As far as overclocking goes, GA-7DX can't boast much. The only option an overclocker can find useful is the opportunity to change the FSB frequency with the help of a set of dip-switches, so that it is equal to one of the following values: 95, 100, 103, 105, 110, 133MHz. In other words, there is no way to change manually the CPU clock frequency multiplier, Vcore or Vio. Although you still can change the clock frequency multiplier and Vcore without the corresponding support from the mainboard, by means of simply closing and breaking the Golden Bridges, you have to admit that it would have been much better if the mainboard had saved us time and trouble experimenting with the processor Golden Bridges.

So, the only thing an overclocker can do with this mainboard is to overclock the CPU with a 200MHz FSB by means of increasing the FSB frequency. By the way, a lot of Duron processors allow setting this value to a very high level. However, you will hardly be able to enjoy this advantage to the full extent, because GA-7DX lets you change the FSB frequency with very large increments and there are no supported values at all between 115MHz and 133MHz.

Before we pass over to the practical investigation, we should point out that we didn't experience any problems with our Gigabyte GA-7DX, which is quite surprising, since we had only an engineering sample and not a mass piece. Although AMD-760 used to have some stability problems when working with PC2100 DDR SDRAM, GA-7DX proved highly reliable and stable throughout the whole testing period with both: PC1600 and PC2100 DDR memory.

Testbed and Methods

Gigabyte GA-7DX was the second mainboard supporting DDR we managed to get at our disposal. Nevertheless, it was the first product based on AMD-760 chipset that's why we will do our best to go as deep into details as possible. We compared the performance of Gigabyte GA-7DX mainboard working with PC2100 DDR SDRAM and PC1600 DDR SDRAM with the performance of a system with VIA KT133 chipset and PC133 SDRAM.

So, there were the following three testbeds assembled for our investigation:

All of them worked with Microsoft Windows 98 SE.

Performance

Before passing over to the detailed study of Gigabyte GA-7DX performance, let's see how fast the memory bus of AMD-760 chipset supporting PC1600 and PC2100 DDR SDRAM works. For this purpose we as usual resorted to SiSoft Sandra 2001 benchmark:

The results of this test are hardly surprising for us now. In the previous reviews we saw that with the DDR SDRAM the memory subsystem performance increased by up to 60%. Now when transferring the data with the help of ALU, the performance gain obtained due to the PC1600 DDR memory makes 39%, and due to PC2100 DDR SDRAM - 46%. In case the FPU is involved into memory operations, the benchmark shows even higher values: PC1600 DDR SDRAM provides 48% performance growth and PC2100 DDR SDRAM - 59%. We should also point out that the performance doesn't grow that greatly when we switch from PC1600 to PC2100 even if the FSB frequency changes from 200 to 266MHz. In the first place it means that the 200MHz processor bus isn't a bottleneck for the system with PC1600 DDR SDRAM, and it is solely the memory bus bandwidth that matters.

This benchmark models the system performance in typical office applications and shows that using high performance DDR SDRAM in business applications is absolutely unjustified. The maximum performance gain we managed to achieve on our Gigabyte GA-7DX with PC2100 DDR SDRAM made only 3% compared to the results we got with PC133 SDRAM.

This test works just the same way as the previous one with that only difference that Content Creation Winstone 2001 models the system functioning in the content creation applications, such as Adobe Photoshop and Macromedia Dreamweaver. Since all of them very often work with large data packs, AMD-760 combined with PC2100 DDR SDRAM allows getting 11% higher performance compared to the results obtained for KT133. The results shown by a system with PC1600 DDR memory are not much lower: the performance gain compared to KT133 based system makes 9%.

SYSmark 2000 is another benchmark measuring the CPU performance in 12 office and content creation applications. However, the performance of the CPU is taken for each application separately that's why the performance differences between the systems with different memory types (and hence with different memory bus bandwidths) appear smaller than in Winstone, where the applications are run all at the same time. Nevertheless, Gigabyte GA-7DX mainboard with PC2100 DDR SDRAM is 8% faster than with PC133 SDRAM. PC1600 DDR SDRAM proves very close to PC2100 memory: the difference between them makes only one single point. Let's take a closer look at SYSmark 2000 results:

Here DDR SDRAM guarantees a 7-8% performance gain.

The results obtained here are very similar to the previous diagram. It's very interesting to see that the performance of Gigabyte GA-7DX appeared independent of the DDR memory type used with it. In both cases, with PC1600 as well as with PC2100, the performance remained unchanged although bandwidths of the processor and memory buses were different. It can be probably explained by the fact that PC1600 usually has CAS 2 latency and PC2100 - CAS 2.5, while SYSmark2000 usually takes into account the memory latency when taking the performance of the mainboards tested.

This time we didn't leave out the professional 3D-modelling software called 3D Studio MAX R3. When testing, it measures the time required for Anisotropic Wheel scene rendering at the resolution set to 800x600. So, the smaller value denotes faster performance. As you can see from the diagrams, a combination of the new DDR memory and an AMD-760 based mainboard allows making this operation only 1 second faster. Well, nothing to be surprised with, since the major workload during the scene rendering in 3D Studio MAX R3 is laid upon the processor FPU and not upon the system memory bus.

Data compression however, goes on 23% faster if we have a system built with PC2100 DDR SDRAM and an AMD-760 based mainboard, than in case of the regular PC133 SDRAM. The DDR memory owes its victory to LZW algorithm used in WinZIP, which operates large amounts of data. As for the results of slower memory, PC1600 DDR SDRAM, it managed to prove 18% faster in WinZIP than the system based on VIA KT133.

We have also checked how fast our review participants are when encoding mp3-files in a popular AudioCatalyst application. For this purpose we used a specially created 100MB wav-file. As you can see from, the charts, the DDR platform built on AMD-760 chipset proves only 7% faster than the competitors, which is not that much at all.

And now we suggest taking a look at the gaming applications to find out what these systems are worth there. To begin with, come the results obtained in a synthetic 3DMark2000.

At a relatively low resolution, when neither AGP bus, nor the graphics card fillrate restrict the system's performance, AMD-760 appears considerably faster than the system based on KT133 chipset. The system with a mainboard on AMD-760 + PC2100 DDR SDRAM turned 14% faster, while in case of PC1600 - 11%.

The higher gets the resolution, the more important appears the graphics subsystem performance of the entire system. That's why different memory types can't influence the overall performance as greatly as in the previous case. Nevertheless, Gigabyte GA-7DX still won about 5-6% from the system built on KT133 and equipped with PC133 SDRAM.

The system performance in Quake3 depends on the memory bus bandwidth quite strongly. Therefore, as soon as we tried DDR SDRAM, we got a significant increase in fps rates. The diagram shows that an AMD-760 based system with PC2100 DDR memory leaves a system built on KT133 and equipped with PC133 SDRAM over 19% behind. Even the use of PC1600 DDR memory will guarantee a pretty tangible performance growth: 14%. However, you should bear in mind that we ran the test at the lowest resolution that's why the graphics subsystem didn't tell on the overall performance at all.

As soon as we increase the resolution, the performance difference starts getting smaller. Nevertheless, Gigabyte GA-7DX retains its leadership running 8-10% ahead of all.

Quake3: Team Arena works with larger textures that's why the performance difference is not so great as in the regular Quake3 Arena. Anyway, the system with AMD-760, a CPU supporting 266MHz FSB and PC2100 DDR memory managed to achieve a 17% performance gain compared to the system with PC133 SDRAM. As soon as we replaced the CPU with the one supporting only 200MHz FSB and installed PC1600 DDR memory, the performance difference dropped down to 13%.

At the resolution set to 1024x768x32 the picture was just like in the regular Quake3. AMD-760 based system with DDR SDRAM left the system with PC133 SDRAM 9% behind.

In Unreal Tournament DDR memory provided the growth in performance equal to 8-10%.

Since the system performance in Unreal Tournament depends mostly on the CPU and the memory subsystem, the resolution changes do not tell on the testing results. Gigabyte GA-7DX on AMD-760 again surpassed its competitors by 9-12%.

MDK2 is a typical gaming application of the past generation, because this game uses a relatively small amount of polygons. The DDR memory says its word here as well: PC2100 increases the performance by 15% and PC1600 - by 10%.

With the increase in the resolution, the performance gain achieved by AMD-760 gets a bit lower: 7-9%.

The last gaming application, which we decided to use in our review, was Mercedes-Benz Truck Racing demo version. This truck racing simulator is a good example of the latest generation games, which use a lot of textures and a complex geometric and physical model. This is probably one of the reasons why the system performed in this benchmark just like in Quake3: with PC2100 DDR SDRAM on board the performance grew by 18%, and with PC1600 DDR SDRAM - by 15%.

Increasing the gaming resolution doesn't lead to any drastic changes. Even at 1024x768x32 the physical and geometric models remain so complicated that the CPU and the memory get loaded much higher than the graphics subsystem. That's why the results simply repeat those shown in the previous test.

AMD-760 Against ALi MAGiK 1

We didn't include the comparison of the today's two Socket A DDR chipsets in the main part of our review on purpose. The thing is that Iwill KA266-R mainboard based on ALi MAGiK 1 chipset and Gigabyte GA-7DX mainboard based on AMD-760 chipset we had in our testlab weren't the final products, but just engineering samples. Therefore, they couldn't really show what the final mainboard versions would be capable of. Nevertheless, we can't absolutely neglect the opportunity to make even a preliminary comparison of these two boards and chipsets.

To carry out the comparative tests we selected the system described above built on Gigabyte GA-7DX mainboard and a similar system built on Iwill KA266-R mainboard.

As you can see from the diagrams above, ALi MAGiK 1 falls behind AMD-760 in all the tests except Business Winstone 2001. And the greater the application loads the memory bus, the larger is the performance gap between the two chipsets. This means that at present the memory controller implemented in AMD-760 is better than that implemented in ALi MAGiK 1. Although the situation may change by the time the final chipset versions and the mainboards based on these versions come out. Nevertheless, now AMD-760 shows higher performance than ALi MAGiK 1 in applications requiring high memory bus bandwidth. And sometimes AMD-760 with PC1600 proves faster than ALi MAGiK 1 with PC2100 memory.

Conclusion

Well, let's sum up. As our tests showed, using new AMD Athlon processors with 266MHz FSB in systems built on AMD-760 chipsets and equipped with PC2100 DDR SDRAM can provide a considerable increase in performance: about 15-20%. This is somewhat higher than the performance gain we observed in our previous tests of another DDR chipset, ALi MAGiK 1. Note that even with a CPU supporting only 200MHz FSB and PC1600 DDR SDRAM the performance grew quite tangibly: by 10-15%.

We should also point out that the gaming applications care much more about the memory bus bandwidth than content creation and office apps. Moreover, in the latter case the use of the DDR memory hardly makes any influence on the system performance at all.

As far as Gigabyte GA-7DX mainboard goes, we should point out that Gigabyte introduced this revolutionary product just in time. This mainboard will be one of the first products based on AMD-760 chipset to appear in the mainboard market. No doubt, it will find its place in the market due to traditionally high stability provided by Gigabyte and high performance ensured by AMD-760 chipset, DDR memory, which bandwidth is twice as high as that of PC133 SDRAM, and a new 266MHz FSB.

However, you shouldn't disregard the fact, that Gigabyte GA-7DX doesn't have any special features for CPU overclocking, unfortunately. That's why we would recommend this mainboard only to those users who are looking for a stable and reliable system and aren't willing to overclock their processors. In this case Gigabyte GA-7DX will prove 100% up to your expectations.