SiS 672FX is a chipset with integrated graphics targeted to low-end socket LGA775 motherboards. We’ve got from SiS a reference board for this chipset and since motherboards based on the same chipset usually achieve similar performance, you can have a clue on what performance to expect from motherboards based on SiS 672FX.
A reference board is a motherboard manufactured by the chipset maker to make internal tests and also to ship to their partners (i.e., motherboard manufacturers) so they can create their own products based on the given chipset.
It is important to have in mind that not all features provided by the chipset are available on all models based on it. It is up to the motherboard manufacturer to choose which features they want on their models. For example, the reference board had two x1 PCI Express slots, two standard PCI slots and one CNR slot, but products based on SiS 672FX may come with less slots.
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Figure 1: SiS 672FX reference board.
SiS 672FX is a low-end chipset with several limitations. Its memory controller allows only single-channel mode, meaning that this chipset accesses the memory at half the speed other chipsets available for the socket LGA775 chipset can. It also only supports DDR2 memory up to DDR2-667, at least officially. On our tests we configured our memory modules at 800 MHz and they worked just fine. This chipset also only supports two memory sockets. Another limitation is that this chipset does not support the new 1,333 MHz FSB, but it accepts all 1,066 MHz-based socket LGA775 CPUs.
As mentioned SiS 672FX has integrated graphics (“on-board video”), based on the Mirage 3+ graphics engine, which is a truly DirectX 9.0 (Shader 2.0) engine. The graphics engine runs at 300 MHz. We asked SiS twice about the number of pixel shader engines and vertex shader engines this chipset has and they ignored these questions. On other reviewing websites we could see that SiS 672FX does not feature a vertex shader engine, this stage being processed by the system CPU, i.e., software-based vertex shader.
Even though SiS 672FX has integrated graphics, it supports one PCI Express x16 slot. Keep in mind that motherboard manufacturers in order to cut costs may offer SiS 672FX-based motherboards without this slot, but this limitation is of these particular motherboard models.
The south bridge chip defines other features that will be found on SiS 672FX-based motherboards. The reference board we got used a SiS 968 south bridge.
SiS 968 main features are:
- One ATA-133 port;
- Two SATA-300 ports, supporting RAID 0, 1 and JBOD;
- Eight USB 2.0 ports;
- Two PCI Express x1 slots;
- Gigabit Ethernet;
- High Definition Audio (eight channels, up to 192 kHz, 32 bits).
Keep in mind that the motherboard manufacturer may choose not to use all features provided by the south bridge chip.
Also, for the LAN port, the manufacturer needs to add a chip on the motherboard to make the interface with the physical layer. On SiS reference board this chip was SiS 196. To cut costs the motherboard manufacturer may use a Fast Ethernet (100 Mbps) chip.
As for the integrated audio, it is very important to keep in mind that the final specs will depend on the codec used, which is a small chip located on the motherboard. On the reference board SiS used a Realtek ALC883, which has a 95 dB signal-to-noise ratio (SNR) and 192 kHz maximum sampling rate for its output and an 85 dB signal-to-noise ratio and 96 kHz maximum sampling rate for its input, both with 24-bit resolution. The output specs of this codec are fair for Average Joe, but the input specs are simple too low for today’s standards.
In summary, the final features of the motherboard depend a lot on the components the motherboard manufacturer chooses.
Now let’s take a look at its performance.