Test impressions/launch details

The SiS 648 reference motherboard

The board layout of the SiS 648 reference motherboard is slightly different than the SiS 645DX board. Minute component changes were made, although at a quick glance some enthusiasts would hardly notice the difference.

Unlike SiS 645DX, the SiS 648 reference board we received lacked a heatsink on the North Bridge of the chipset. Prior to SiS 645DX, all the SiS motherboards we’ve received also shipped without a heatsink on the North Bridge. This keeps costs down for motherboard manufacturers, although we’ve noticed many retail SiS Pentium 4 motherboards with heatsink/fan combo units. Under heavy load the SiS 648 chip would get hot to the touch at 533MHz, but not unbearable. While previous SiS North Bridges were cooler, we still don’t think motherboard manufacturers will be forced to implement active cooling solutions on their respective products.

Stability

Stability of the reference board was excellent. We didn’t encounter a single lockup or crash in Windows XP during our testing while we were running the system within spec. When we attempted to run three DDR333 modules on the SiS 648 system some applications would occasionally crash, kicking us back to the Windows desktop but not locking up the system. The chipset doesn’t officially support three DDR333 modules, so the fact that it would run many Windows applications with no problems was a pleasant surprise, but we wouldn’t recommend it for consumers in mission-critical applications.

Compatibility

We mixed and matched many DDR266 and DDR333 modules from a wide variety of manufacturers and didn’t encounter any problems with the SiS 648 reference board. We’re still unsure how well DDR400 memory will ultimately run on the SiS 648 platform, as the only module we have was supplied by SiS for our testing.

Availability

Since we just discussed memory modules, we’ll start there first. As we just stated, SiS supplied us with a DDR400 module manufactured by TwinMOS Technologies. TwinMOS is a relatively new memory manufacturer that is based in Taiwan and is primarily available in the Asian market. TwinMOS DDR400 modules are in full production now and should begin slowly trickling onto the market, although we’re unsure if that applies to those of us here in the US. Besides TwinMOS, KingMax, Mushkin, and Corsair Microsystems are also currently shipping DDR400 memory modules.

In terms of motherboard availability, we’ve been told that ASUS, ABIT, ECS, and Gigabyte will likely be among the first to market with SiS 648-based motherboards. In fact, ASUS’s board (the P4S8X) will ship with Serial ATA hard drive support. ASUS Taiwan predicts availability in the July/August timeframe, although ASUS USA was less willing to confirm that date.