X-bit labs

SiS655 - New Dual-Channel Chipset. Gigabyte GA-8SQ800 Ultra – First SiS655 Based Mainboard (page 4)

Category: Chipsets

by Ilya Gavrichenkov

[ 03/21/2003 | 01:49 AM ]

Testbed and Methods

The goal of the today’s review is to reveal the performance level of the new dual-channel DDR SDRAM chipset from SiS – SiS655. We will compare it with modern chipsets from Intel: E7025, i850E and i845PE. All the participating chipsets were benchmarked in all possible work modes with a Pentium 4 3.06GHz CPU (Hyper-Threading was activated).

We tested SiS655 in three work modes: single-channel 64-bit, single-channel 128-bit and dual-channel 64-bit memory access modes. The memory clock-rate was set at 266, 333 and 400MHz. Intel chipsets were also tested in all available work modes.

As a result, our testbeds were configured as follows:

All the benchmarks were run in Microsoft Windows XP Professional. The mainboards were set to maximum performance by means of setting the lowest possible timings our memory modules allowed (2-2-2-5 at 266MHz memory frequency, 2-2-2-6 at 333MHz memory frequency and 2-3-3-7 at 400MHz memory frequency). By the way, we used high-quality Corsair XMS3200 DDR SDRAM.

Performance

First of all, let’s run the synthetic Cachemem benchmark to test memory controllers of the reviewed chipsets.

Let’s analyze the results. First of all, SiS655 certainly justifies our hopes and shows high performance with the memory. Thus, this chipset with dual-channel DDR333 and DDR400 outperforms i850 with dual-channel RDRAM as well as single-channel i845PE. In fact, there is only one worthy rival – Intel E7205. Although Intel’s chipset uses slower DDR266 memory, lower latency helps it to show high results. We should also keep in mind that the peak bandwidth of the Pentium 4 bus is 4.2GB/s, which exactly corresponds to the throughput of dual-channel DDR266.

Meanwhile, we should note that the use SiS655 in dual-channel mode with fast memory types, like DDR333 and DDR400, will allow increasing the write and copy speeds as well as lower the memory latency.

Comparing the results of SiS655 with DDR400 and DDR333, we see that nominally faster DDR400 is greatly hindered by its high latency. It means that SiS655 might be faster with DDR333 in many applications. Moreover, SiS optimized its chipset exactly for this memory type.

There is also a perceptible difference between the two dual-channel modes of SiS655. 128-bit memory access provides higher effective bandwidth, while 64-bit mode – lower latency. So, we may suppose SiS655 would show its maximum performance in 64-bit dual-channel DDR333 SDRAM mode. We will see it in real applications later in the article.