SiS 645: Pentium 4 DDR - Take II

Final Words

It's the start of a new month and we get another DDR chipset for the Pentium 4 platform. The only difference this time around is that the SiS 645 has Intel's blessing which is worth its weight in gold to motherboard manufacturers. Ever since Intel and VIA filed suits against each other, most motherboard manufacturers have stepped out of the conflict and refused to release P4X266 based solutions. With the 645, SiS may be the knight in shining armor that a lot of the manufacturers are looking for to provide them with a solid DDR solution for the Pentium 4. The official support for DDR333 SDRAM is an added perk that will give you another 0 - 5% performance improvement in most cases, but definitely not needed to get good performance out of the SiS 645.

The SiS 645 doesn't hold much of a performance advantage over the VIA P4X266 or the Intel 850 but it should be pointed out that it is technically faster than both of those solutions. And the timing on the 645, albeit a little later than SiS would have liked to gain the full effect of a "legitimate" Pentium 4 chipset, couldn't have been better. Motherboard manufacturers have clearly expressed interest in the solution and will most likely pursue 645 based designs unless things settle between Intel and VIA very soon. There is one kink in this plan for chipset domination however, and that is Intel's own DDR solution for the Pentium 4.

Due out in the first quarter of next year (remember that's less than 4 months away) is Intel's 845-D chipset with support for both DDR200 and DDR266. If the SiS 645 isn't found on motherboards until November or December in mass-quantities, then it may be difficult to force many people to go with a SiS based solution instead of waiting two months for an Intel solution. Granted that the SiS 645 based motherboards will be cheaper, but considering how reliable the first round of 845 motherboards were and the early proclamation of the 845 being the "next BX chipset" by most manufacturers in Taiwan, it will be difficult to justify the 645. This brings us to another point about chipset releases. Somewhere along the lines it became "acceptable" for chipsets to be released without a sign of motherboards for weeks or even months to come. Compare this to an Intel chipset launch where motherboards (quite a few) are available on launch day and you'll see why we're always uneasy with talking about performance when the only board available is one supplied to you by the manufacturer of the chipset. In the case of the SiS 645 we actually expect shipping boards to be faster than this engineering sample, but competing chipset manufacturers should start coordinating their chipset launches better with the motherboard manufacturers that will be implementing those chipsets.

The first manufacturer producing 645 based motherboards is, as you'd expect, ECS. You'll remember that ECS also had the world's first widely available SiS 735 based motherboard which actually turned out to be a pretty reliable design from ECS. Their 645 based motherboard should be very cheap and we're hoping will boast a similar if not slightly improved overall build quality to the ECS K7S5A (SiS 735). Boards like the upcoming offering from ECS, as well as solutions from ASUS and MSI (provided that they actually hit the market) could redefine the entry-level Pentium 4 standards. Instead of having to deal with an underperforming PC133 SDRAM equipped 845 board, a DDR266 board with the SiS 645 could be had. For OEMs, a similar scenario exists but with the upcoming 650 (w/ integrated video) as the chipset of choice. Even in spite of Intel's upcoming 845-D, there won't be another Pentium 4 chipset with integrated graphics other than the P4M266 for quite some time; and an integrated graphics core could definitely saturate the remaining bandwidth offered by DDR333.

Setting concerns regarding Intel aside, it does look like SiS does have another winner with the 645. This is oddly reminiscent of the release of the 735 chipset; the only question that remains is whether this spark will ignite another fire within VIA causing a P4X266A to be released down the road. It's unlikely that VIA can get more performance out of their memory controller without some more serious modifications, potentially adding DDR333 support.

Will VIA shorten the life-span of yet another SiS chipset? From an OEM standpoint, probably not because of the strengths in SiS' upcoming integrated solution. But when looking at the 645 itself, chances are that if VIA doesn't, Intel will.