DFI 748-AL: First Look at SiS 748

DFI 748-AL: Stress Testing

We performed stress tests on the DFI 748-AL in these areas and configurations:

1. Chipset and motherboard stress testing, which was conducted by running the FSB at 212MHz; and
2. Memory stress testing, which was conducted by running RAM at 400MHz with 2 DIMM slots filled and at 400MHz with 3 DIMM slots filled at the lowest memory timings possible.

Front Side Bus Stress Test Results:

As standard practice, we ran a full range of stress tests and benchmarks to ensure the DFI 748-AL was absolutely stable at each overclocked FSB speed. These stress tests included Prime95 torture tests, which were run in the background for a total of 24 hours.

In addition, we ran several other tasks — data compression, various DX8 and DX9 games, and apps, like Word and Excel — while Prime95 was running in the background. Finally, we ran our benchmark suite, which includes ZD Winstone suite, Unreal Tournament 2003, SPECViewperf 7.0, and Gun Metal Benchmark 2. While we were able to boot and run some tests at speeds as high as 217MHz FSB at default voltage on the 748-AL, 212MHz was the highest FSB overclock that we were able to achieve at default voltage with the Asus without encountering any reliability issues.

Memory Stress Test Results:

The memory stress test is very simple, as it tests the ability of the 748-AL to operate at its officially supported memory frequency (400MHz DDR) at the lowest supported memory timings that our Corsair TwinX LL modules support. The SPD timings for the Corsair v1.2 modules is 2-2-3-6, but without any real means to set individual memory timings on the 748-AL, we had to rely on other utilities to report real memory timings. CPUZ (www.cpuid.com) does not recognize the SiS 748 chipset memory controller, and we could not use it to determine memory timings. We had to depend on results reported in SiSoft Sandra Max3 Memory Test for memory timings. Sandra recognized the chipset correctly, but reported memory timings may not be 100% correct.

Stable Dual DDR400 Timings (2/3 banks populated)
Clock Speed:	200MHz
Timing Mode:	Performance
CAS Latency:	2.5
Bank Interleave:	4
RAS to CAS Delay:	4T
RAS Precharge:	5T
Precharge Delay:	4T
Command Rate:	N/A

We did some experimenting with the “Normal” and “Performance” selections in BIOS. Normal memory timings are reported to be 2.5-4-4-8 in Sandra. When Performance is selected, CAS settings can be chosen, but CAS 2 would not work with the Corsair 3200LL modules or any other high-speed module that was tested. The lowest setting that works is “Performance”, “CAS 2.5” and Sandra timings are reported as 2.5-4-4-5.

Filling all 3 available memory banks is much more strenuous on the memory subsystem than testing 2 banks. With all 3 banks filled, the DFI 748-AL had no problems with the same timings that worked with 2 dimms.

Stable DDR400 Timings (3/3 banks populated)
Clock Speed:	200MHz
Timing Mode:	Performance
CAS Latency:	2.5
Bank Interleave:	4
RAS to CAS Delay:	4T
RAS Precharge:	5T
Precharge Delay:	4T
Command Rate:	N/A

We were pleased to see the DFI run with stability with 3 DDR400 dimms. With the limited Memory Timing options available, we really can't tell you much about memory timings with 2 and 3 dimms. Normally, 3 dimms requires timings a bit slower than 2, but until DFI adds memory timings in the release BIOS, we really can't tell you the fastest timings that will work on the 748-AL. It’s worth stating again that the real world performance difference between aggressive memory timings and more relaxed memory timings, such as SPD, are often very small. That is more than just words in this 748-AL review, as you will see in performance tests using these very slow memory timings.

We tested all these memory timings using several stress tests and general applications to guarantee stability. Prime95 torture tests were successfully run at the timings listed in the above charts. We also ran 3DMark and Super Pi. None of these stress tests created stability problems for the DFI 748-AL at these memory timings.