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Not long ago we wrote about VIA Apollo Pro266 chipset, the first core logic for Pentium III with DDR SDRAM support. That time our tests revealed that higher performance of this memory type produces no effect on the overall system performance. However, for those tests we used a reference board by VIA, so its performance could differ from that of the final VIA Apollo Pro266-based mainboards. That's why we looked forward to test the first real boards based on this chipset. At last our patience was rewarded and we got hold of one of the first mainboards built on VIA Apollo Pro266 - Gigabyte GA-6RX.

Of course, we couldn't lose a chance like that and dedicated a whole article to this promising newcomer. It is actually the first mainboard by Gigabyte, which is equipped with a whole bunch of overclocking functions.

Closer Look

A single glance at Gigabyte GA-6RX is quite enough to understand that presently it is one of the most advanced mainboards for Socket370/FC-PGA processors and enjoys a great variety of functions. Here are the specs:

Gigabyte GA-6RX
Supported CPUs Intel Pentium III/Celeron FC-PGA
Chipset VIA Apollo Pro266 (VT8633 + VT8233)
FSB Frequencies 66, 75, 78, 90, 100, 105, 110, 115, 124, 130, 133, 136, 140, 145, 150MHz
Overclocking Friendly Features Vcore, Vio and Vmem
Memory 4 184-pin DIMM slots for PC1600/PC2100 DDR SDRAM
AGP slot AGP Pro
Expansion slots (PCI/ISA/AMR) 5/0/1
USB ports 4
Integrated Graphics No
Integrated Sound Creative CT5880
Additional features Promise ATA/100 RAID controller
DualBIOS technology
Form-Factor ATX, 305x245mm

Although Gigabyte GA-6RX is equipped with a standard Socket370, there are some changes in the list of the supported CPUs in comparison to the previous boards. First, following the example of some other manufacturers, Gigabyte has rejected the support of PPGA Celeron CPUs. Well, we doubt that many users will be striving to use this out-dated processor with a DDR SDRAM mainboard, but there still may be some people willing to do it. Then, it is no secret now that Pentium III 1.13GHz CPUs that are due in the nearest future will feature a new D0 core, working at a higher voltage of 1.75V. Naturally, it will cause greater heat dissipation, and consequently larger coolers will be needed. Gigabyte has taken this fact into consideration, so the capacitors on GA-6RX, serving to stabilize the power supply, are moved farther away from Socket370. This way, installing very large cooling systems should cause no problems whatsoever.

It's a pity that in the market there are yet no chipsets compatible with Pentium III on Tualatin core, which are due in Q3 2001. The matter is that this core will require lower voltage (1.2V) for its AGTL+ bus, thus new core logic will be needed. For this reason Tualatin will not be supported by VIA Apollo Pro266-based mainboards, including Gigabyte GA-6RX as well. Still, according to VIA's plans, it will introduce a new DDR chipset to support this core, Apollo Pro266T. This core logic is scheduled for mass production only in March. So, currently Gigabyte GA-6RX can allow using DDR SDRAM just with common FC-PGA CPUs, Celeron and Pentium III.

As a rule, Gigabyte provides its mainboards with as many DIMM slots as possible and users can feel free about using different DIMM modules. GA-6RX hasn't broken the tradition. It can boast four DIMM slots that are a maximum for VIA Apollo Pro266 chipset. Surely, these are 184-pin slots and they are intended for PC2100/PC1600 DDR SDRAM. To put it all in figures, as long as larger DDR SDRAM modules - up to 1GB - should appear soon, Gigabyte GA-6RX can work with a total memory capacity of 4GB.

Some manufacturers, among them Chaintech and Shuttle, are about to announce VIA Apollo Pro266-based mainboards, that will be equipped with 184-pin and 168-pin memory slots at a time. On the one hand, a move like that will allow using boards of the kind with DDR SDRAM as well as with PC133 SDRAM. On the other hand however, the layout will inevitably become much more complicated, so in the long run the stability may be rocked. That's why, since Gigabyte cares a lot for the reliability of its products, the company gave up developing a solution like that and confined itself to introducing the support of only DDR SDRAM to its new mainboard.

Unlike other DDR chipsets, VIA Apollo Pro266 lets clocking the memory and FSB asynchronously. Practically, it means that in case of processors with 133MHz FSB, Gigabyte GA-6RX can work not only with PC2100 DDR SDRAM, but also with 100MHz PC1600 DDR SDRAM. Subsequently, if we take processors with a 100MHz bus, we can adjust the memory bus of GA-6RX to work at 133MHz, that is to support PC2100 DDR SDRAM. The settings of the memory subsystem on Gigabyte GA-6RX are changed through BIOS Setup, which features CAS latency and memory frequency parameters, alongside with Memory Bank Interleave:

Since GA-6RX is intended mainly for advanced users, Gigabyte has made up its mind to provide the board with an AGP Pro slot. Unlike most other boards equipped with this slot that support only graphics cards with under 50W power consumption, GA-6RX is able to work even with 110W graphics cards. In this case however, a power supply unit with an additional ATX12V Out should be used, like we saw on Pentium 4 platforms. GA-6RX has a special connector for this cable, which is situated near AGP Pro slot (unfortunately, the tested sample wasn't equipped with such a connector).

It should be pointed out that the developers moved AGP Pro slot far enough from the memory slots, so the graphics cards installed will not hinder the manipulations with DIMM modules, as it usually happens by other boards. The vacant space is occupied by an AMR slot (we have no idea, why Gigabyte hasn't chosen a smarter ACR slot for its board). Moreover, since the AGP Pro slot was moved somewhat aside, it leaves enough space only for five PCI slots. On the left side of the board one could easily place, for instance, a shared ISA slot, but GA-6RX does not support this bus. Indeed, this isn't at all surprising, since the new South Bridge, which is used in VIA Apollo Pro266, VT8233, doesn't feature an integrated PCI-to-ISA bridge any longer, that is why adding an ISA slot would have required more additional microchips.

However, Gigabyte has implemented some other opportunities on its GA-6RX that make this board a sheer advanced-user-oriented product. First of all, it should be noted that the board features an integrated ATA/100 IDE RAID controller. The company used Promise PDC20265R microchip, which is a RAID version of Promise PDC20265 chip (this chip is the heart of Promise Ultra100 controller). In its turn, the controller BIOS, which is integrated into that of the mainboard, is a "Lite" version of the of Promise FastTrak100 controller BIOS. The difference is that the RAID controller on Gigabyte GA-6RX does not support 0+1 level RAID and works only in RAID 0 (mirror) or RAID 1 (stripe) mode. It is the controller BIOS that manages the controller and carries out all the operations connected with the creation of disk arrays.

It's noteworthy that theoretically the BIOS of ATA/100 IDE RAID controller offers an opportunity to adjust the size of a stripe block, however, this function does not work, so the block size is 64KB, no matter what the settings are.

One of the features provided by ATA/100 IDE RAID controller on GA-6RX is the possibility to make it operate as a regular Ultra ATA/100 controller. It is a reasonable thing if you deal with separate disks. As our earlier tests show, a common Promise Ultra100 controller proves to have higher performance than FastTrak100 with only one disk connected to it.

There are three ways to connect the hard disk drives to GA-6RX: via the South Bridge of the chipset, via the Promise controller working as RAID or as a common ATA/100 controller. It seemed interesting to us to compare, which of the above listed variants is the best, i.e. which of them secures higher performance. For this purpose we tried all the ways one by one and checked the performance of the disk subsystem with the help of WinBench99 1.2:

We were really surprised as we saw the results. Indeed, when we deal with a single hard disk drive, it is better to switch ATA/100 IDE RAID controller to Ultra100 mode. But the most interesting thing is that when the HDD is connected to a regular IDE-controller, which is integrated into the South Bridge, the performance of the disk subsystem proves to be much lower than in case of Promise controller. It's even more surprising, since the Bridges of the chipset are connected not by means of a PCI bus, like the external controller, but via V-Link bus, which is tangibly faster (its bandwidth is as great as 266MB per second). Obviously, it's just a matter of drivers, like in most situations with VIA chipsets. VIA Apollo Pro266 core logic is rather fresh and that's why its support in IDE Bus Master driver isn't that well-optimized yet. We should draw your attention to the fact that the current drivers support the ATA/100 mode, which is backed up by the synthetic tests, we used to check, how fast the data is transferred from the HDD buffer.

Alongside with the RAID controller, Gigabyte GA-6RX features an integrated hardware PCI sound controller, Creative CT5880, which is evidently better than the software AC'97 sound. A remarkable peculiarity of the sound subsystem is a four-channel Sigmatel STAC9708T codec. From the practical viewpoint it means that the sound card, integrated on GA-6RX, is a four-channel one and you can use the Line-In to plug a second pair of speakers.

Speaking of Gigabyte GA-6RX characteristic features, we can't fail to mention DualBIOS, a brand technology, which you can meet in the company's best products since June 1999. This technology is based on two Flash memory chips, storing two copies of BIOS - the primary and the reserve one. As a rule, GA-6RX turns to the primary copy, but in some urgent situations, for example, if the primary copy is damaged by a CIH-like virus or merely as a result of improper reflashing, the reserve copy lets not only boot up the system, but also revive the primary BIOS. The functions of DualBios are managed by a special utility, which can be launched before the OS loading if you wish.

The BIOS of GA-6RX is based on AMI BIOS version 1.24a. As the tradition goes, BIOS by AMI is a bit less flexible in setting than the regular Award Modular BIOS v6.0, but it provides some performance gain compared to the other one. This way, it can be hardly treated as a drawback of Gigabyte GA-6RX.

In spite of the impressive variety of chips and slots implemented on GA-6RX, Gigabyte has contrived to arrange all of them on a PCB of a standard size. As a result, there are no problems with hosting this board in any ATX case. Still, the layout is not perfect, mainly due to an inconvenient location of the ATX power supply connector as well as IDE3 and IDE4 connectors. Thus, the power supply cable overhangs the memory and prevents it from proper cooling, and IDE cables will have to stretch across the entire case to reach the Promise controller.


Now it's high time we passed over to the most interesting part of the review. As we have already said, GA-6RX is the first mainboard by Gigabyte, which is provided with all necessary overclocking functions. Evidently, the users have finally forced one of the most conservative companies to give up its principles, so now all the new boards by Gigabyte intended for the DIY sector will offer corresponding opportunities. Let us see, whether Gigabyte's first experience of the kind can be called a success.

The first thing to mention is Gigabyte's faithfulness to the old tradition, implying that the CPU is configured by means of jumpers and dip-switches, but not via BIOS Setup. So, all the overclocking settings are changed in the same way. Naturally, it is not the best variant for running a great number of overclocking tests, but on the other hand, you can stop worrying that the parameters you have set can be lost, when CMOS is cleared. It is hard to say for sure, which of the methods is the most functional, although the present popular trend is to overclock through BIOS Setup.

Among the settings that you may change is FSB frequency, CPU Vcore, the chipset and the memory voltages. To change the FSB frequency, there is a block of eight dip-switches, that offer a range of frequencies to choose: 66, 75, 78, 90, 100, 105, 110, 115, 124, 130, 133, 136, 140, 145, 150?Hz. Actually, the options are not that numerous, but there are no huge gaps between the figures. Nonetheless, this is still insufficient for finer overclocking of the system, especially bearing in mind that there are several other boards that allow changing the FSB frequency with 1MHz increments.

As for Vcore, the things are somewhat better here. The block of 6 dip-switches, which serves for changing this particular parameter, allows changing the voltage in the interval from 1.3V to 2.05V with an increment of 0.05V. As you see, even for the new Coppermine with D0 core and 1.75V nominal Vcore, this value can be increased by 0.3V, that makes a good gain even for extreme overclocking. The only shortcoming of this method of voltage adjustment is the possibility to set it too high and hence ruin the CPU.

Moreover, Gigabyte GA-6RX is equipped with two additional jumpers that allow increasing the chipset and memory voltages by circa 0.1V.

The resume is that Gigabyte's pioneer product with overclocking functions can be called a success. However, the company has anyway a lot to work at. The poor range of FSB frequencies is at the top of the list. So, we can only hope that Gigabyte won't rest on its oars and its future products will please us with greater overclocking freedom.

Testbed and Methods

We have already compared the performance of VIA Apollo Pro266 core logic with that of other chipsets in the article titled: "Pentium III with DDR SDRAM: VIA Apollo Pro266 Chipset Review". The results we obtained on Gigabyte GA-6RX don't differ a lot from those of a reference board based on VIA Apollo Pro266, so in this review we will merely compare the performance of two boards: GA-6RX and one of the present-day favorites, ASUS CUSL2 built on i815 chipset. The tested systems were configured as follows:

  Gigabyte GA-6RX ASUS CUSL2
CPU Intel Pentium III 1GHz
Mainboard Gigabyte GA-6RX ASUS CUSL2
Memory 256MB PC2100 DDR SDRAM 256MB PC133 SDRAM
Graphics Card Creative 3D Blaster Annihilator 2 Ultra (NVIDIA GeForce2 Ultra)

The systems worked in Microsoft Windows 98 SE.


First of all, let us remind you that no outstanding performance gain is to be awaited from DDR SDRAM used on Pentium III platforms. Since the CPU bus bandwidth of Pentium III is no higher than that of PC133 SDRAM, getting a faster memory bus doesn't lead to any increase in performance. In other words, it is the CPU bus that becomes a bottleneck when DDR SDRAM is used, so that the effect made by faster memory subsystem comes to naught.

Keeping this in mind, we were keen to see, whether Gigabyte GA-6RX would be able to overtake one of the performance leaders, ASUS CUSL2 based on i815. To start with, let us have a look at the results we obtained in office applications:

All the three tests that simulate the work in office and content-creation applications indicate that ASUS CUSL2 with PC133 is by all means faster than the DDR platform - Gigabyte GA-6RX. Well, no wonder, since PC133 SDRAM has a little bit lower latency than PC2100 DDR SDRAM, that's why those applications, that are sensible to this characteristic, work faster on ASUS CUSL2.

And what about 3D games?

Since in 3D applications it is not only the CPU but also the graphics card, which transfers the data via AGP bus, GA-6RX manages to slightly surpass its rival.

The same fuss is observed in Quake3. The DDR platform enjoys a moderate overtake.

In Unreal Tournament we can witness a reverse state of things. Combining DDR SDRAM with Pentium III proves no good in this game, so ASUS CUSL2 dashes ahead of Gigabyte GA-6RX.

In MDK2 the platforms have come to almost equal results.

Mercedes-Benz Track Racing is practically the only task where Gigabyte GA-6RX is undoubtedly faster than ASUS CUSL2 with PC133 SDRAM. This brand new game uses a complicated physical model and a great number of textures, so the memory bus is busier exchanging the data with the graphics card, but not with the CPU. It all leads to a 13% advantage of Gigabyte GA-6RX in 1024x768x32 resolution.


The tests we have run prove it once again that the combination of DDR SDRAM with Intel Pentium III yields no tangible performance gain. Only the most recent 3D applications let us declare some advantages of DDR SDRAM platforms. That's why there is barely any sense to switch over to mainboards built on VIA Apollo Pro266 and neglect those based on i815 and the like equipped with PC133 SDRAM. It looks utterly unreasonable to assemble more systems with boards based on VIA Apollo Pro266, since DDR SDRAM costs a lot. Nevertheless, judging by performance and functions, VIA Apollo Pro266 based mainboards represent a good alternative to those built on i815.

As for Gigabyte GA-6RX in particular, so far we have no chance to compare it with similar products by other manufacturers. But we have to admit that this board is a really smart product, nicely designed, with a good set of attractive features. Another thing to mention is the overclocking aptness of GA-6RX, which is a real wonder for a board by Gigabyte.


  • Beautiful performance in memory-requiring applications;
  • CPU overclocking opportunities;
  • DualBIOS technology;
  • Integrated ATA/100 IDE RAID controller by Promise;
  • Stylish outlook.


  • Poor range of FSB frequencies
  • Some design drawbacks.
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