Gigabyte 8S655FX Ultra (SiS 655FX): Price/Performance Reaches a New Level

Gigabyte 8S655FX Ultra: Stress Testing

We performed stress tests on the Gigabyte 8S655FX Ultra in these areas and configurations:

1. Chipset and motherboard stress testing, conducted by running the FSB at 239MHz.
2. Memory stress testing, conducted by running RAM at 400MHz with all four DIMM slots filled and at 500MHz with two of four DIMM slots filled, all 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 that the Gigabyte 8S655FX Ultra 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. Moreover, 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 287MHz FSB and at default voltage on the Gigabyte 8S655FX Ultra, 262MHz was the highest achievable overclock attainable without encountering any reliability issues.

Memory Stress Test Results:

Filling all four available memory banks is more strenuous on the memory subsystem than testing just one bank, which is why we’ve skipped our usual single bank testing with this review and went straight to this often asked about memory configured. Here were our results:

Stable DDR400 Timings (4/4 banks populated)
Clock Speed:	200MHz
Fast Command:	N/A
CAS Latency:	2.0
Bank Interleave:	N/A
RAS to CAS Delay:	3T
RAS Precharge:	6T
Precharge Delay:	2T
Command Rate:	N/A

Except for RAS to CAS delay, we see that the Gigabyte 8S655FX Ultra is an exceptionally well performing motherboard in terms of memory capability. CAS 2-3-2-6 with three banks filled is quite excellent, to say the least. Luckily, this isn’t a rare occurrence, but is worth mentioning because there have been far too many good motherboards that have been crippled due to poor main memory implementation.

Continuing our tradition from our previous Intel motherboard review (ASUS P4P800S-E (848P)), we will be testing how well the 8S655FX Ultra is able to handle speeds of DDR500 and higher. OCZ PC3700 GOLD memory has proven itself capable of well over DDR500 speeds, which is exactly why we used two matched PC3700 GOLD modules for our testing:

Stable DDR500 Timings (2/4 banks populated)
Clock Speed:	250MHz
Fast Command:	N/A
CAS Latency:	2.5
Bank Interleave:	N/A
RAS to CAS Delay:	4T
RAS Precharge:	7T
Precharge Delay:	3T
Command Rate:	N/A

Yes, obviously CAS 2.5-4-3-7 are hardly enviable memory timings, but they are quite decent at such an outrageously out of spec speed like DDR500. The performance penalty for a high RAS to CAS like 4T and a high CAS Latency of 2.5T isn’t as bad as you think. This speed is still slightly faster than ultra low latency modules (CAS 2-2-2-5) running at DDR400 speeds, and the price difference in the end isn’t all that much more. Because of this, you may want to consider high speed memory technologies such as PC3700 (DDR466), PC4000 (DDR500), and PC4200 (DDR533) for the 8S655FX Ultra.

In addition to the above two memory scenarios, we performed some additional memory testing and ended up being even more impressed with the 8S655FX Ultra’s memory performance, Not only was the 8S655FX Ultra able to reach DDR500 with ease, but all the way up to DDR540 without a hiccup! Of course, memory timings were running at a paltry CAS 3-4-4-7, so the performance advantage was totally negated. Still, there’s no denying that the 8S655FX Ultra’s memory performance is impressive nonetheless.

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 Sciencemark (memory tests only) and Super Pi. None of the three stress tests created stability problems for the Gigabyte 8S655FX Ultra at these memory timings.