SiS 756: PCI Express for AMD Socket 939

Basic Features: SiS 756 Reference Board

SiS 756 Reference Board
CPU Interface	Socket 939 Athlon 64
Chipset	SiS 756 Northbridge - SiS 965L Southbridge
CPU Clock Speeds	200 to 255MHz in 1MHz Increments
Memory Speeds	Auto, DDR200, 266, 300, 366, 400
PCIe Speeds	80, 85, 90, 91, 94, 97, 100
PCI/AGP	Fixed at 33/66
Core Voltage	Auto, 1.175V to 1.55V in 0.025V increments
CPU Clock Multiplier	8x-23x in 1X increments
DRAM Voltage	NO Adjustments
HyperTransport Frequency	1000MHz (1GHz)
HyperTransport Multiplier	Auto, 200, 400, 800, 1000 (NO 600 Setting)
HyperTransport Voltage	None
Chipset Voltage	None
Memory Slots	Four 184-pin DDR DIMM Slots Dual-Channel Configuration Regular Unbuffered Memory to 4GB Total OR Registered DIMMs if Selected in BIOS
Expansion Slots	1 PCIe x16 2 PCIe x1 2 PCI Slots
Onboard SATA/RAID	4 SATA 1 Drives by 965L (RAID 0, 1, JBOD)
Onboard IDE/IDE RAID	Two Standard ATA133/100/66 (4 drives)
Onboard USB 2.0/IEEE-1394	8 USB 2.0 ports supported by 965L NO Firewire
Onboard LAN	Gigabit PCIe Ethernet by SiS191/190 Driver
Onboard Audio	7.1 AC'97 Audio by Realtek ALC850
BIOS	AMI

In Reference Board reviews, there is always the mention that Reference Boards are designed for qualification and not for production. This is particularly true with the SiS 756 Reference Board as it was not even designed to fit in a standard case.

Click to enlarge.

The SiS 756 Reference Board is more typical of Reference Boards from the past than some of the recent ones that we have tested. ULi and ATI both supplied boards with a complete range of overclocking options and a design that supported overclocking. The SiS 756 is much more modest - more for qualification than any evaluation of enthusiast level performance.

200 to 255 is too limited in processor clock speed to interest the enthusiast, though it is more than adequate for the average user who may never overclock his motherboard. Particularly troublesome is the missing 600 Hypertransport setting, which is useful in higher overclocks. Voltage is also limited to a modest .05V over-volt with a 130nm Athlon 64.

The 965L south bridge supported a Realtek ALC850 7.1 channel codec that is commonly seen on AMD chipsets. However, the more recent 966 south bridge, combined with the 756, could provide High-Definition (Azalia) audio, like the recently tested ATI Rx480 chipset. This would be a real advantage compared to the basic audio capabilities of the nForce4 chipset.

You will also notice that while the 965L supports SATA and SATA RAID, it does not support SATA2. This may or may not matter to you. SATA2, and in particular SATA2 3.0Gb/s drives, are just now appearing on the market. The new SATA2 drives, even the 3Gb/s variety, offer little performance advantage today, so this may not of importance to you. However, this will likely become a more important feature over time.

It is also worth noting that SiS has not yet announced a Southbridge with SATA2 support. Even the 966 family does not fully support SATA2. The next generation south bridges will likely support this feature.