Socket 939 Chipsets: Motherboard Performance & PCI/AGP Locks

Performance Test Configuration: Chipset Comparison

Performance Test Configuration
Processor(s):	Athlon 64 FX53 Socket 939 (2.4GHz, 1MB Cache) Athlon 64 FX51
RAM:	2 x 512MB Mushkin PC3500 Level II OR 2 x 512MB OCZ PC3500 Platinum Ltd
Memory Timings:	2-2-2-10 Command Rate 1T "Aggressive"" memory setting
Hard Drive(s):	Seagate 120GB 7200RPM SATA (8Mb buffer)
Video AGP & IDE Bus Master Drivers:	VIA 4in1 Hyperion 4.51 NVIDIA nForce Platform Driver 4.15
Video Card(s):	ATI Radeon 9800 PRO 128MB (AGP 8X)
Video Drivers:	ATI Catalyst 4.5
Operating System(s):	Windows XP Professional SP1
Motherboards:	AMD Reference Board MSI MS-6702E (K8T Neo2) nVidia MSI MS-7025 (K8N Neo2)

Benchmarks used either Mushkin PC3500 Level II or OCZ PC3500 Platinum Ltd memory modules. Both DIMMs use Winbond BH5 chips and perform virtually the same in our tests.

All performance tests were run with the ATI 9800 PRO 128MB video card with AGP Aperture set to 128MB with Fast Write enabled. Resolution in all benchmarks is 1024x768x32 unless otherwise noted. While we do have an ATI X800 PRO in the lab, all testing used our standard video test configuration with the ATI 9800 PRO 128MB. This allows the best comparison of test results to CPU tests in our Socket 939 launch review and earlier motherboard benchmarks. AnandTech will update the video card test standard to one of the new generation video cards as soon as the new cards are widely available in the market. We have not yet determined our new video test standard as we have not yet tested shipping retail cards from either nVidia or ATI.

Memory Timings

Prior to benchmarking, a complete series of memory bandwidth tests were run on the Socket 939 motherboards using memtest86. We found the fastest memory timings for both the nForce3-250 and K8T800 PRO to be 2-2-2-10. tRas timings produced about the same bandwidth at any setting in the 9 to 11 range on both test motherboards, but memory bandwidth decreased slightly below a tRas setting of 9 and above a tRas setting of 11. In the tests of performance of tRas settings from 5 to 15, the worst performance in the range was at tRas 5. On the Intel platform, best performance is generally achieved at the fastest timings, but tRas 10 was fastest on Athlon 64 platforms. The memory bandwidth improvement at tRas 10 was only 2% to 4% over tRas 5 and 6 depending on the speed, but the performance advantage was consistent across all tests. Since best performance was achieved at 2-2-2-10 timings, all Athlon 64 benchmarks were run at a tRas setting of 10.

The Importance of Command Rate

Socket 754 Single-Channel motherboards performed best with a memory Command Rate setting of 1T in BIOS, but that generally was a stable option with only one DIMM. 2 or more DIMMs normally required a 2T Command Rate setting for most stable performance. There was a performance increase at the 1T Command Rate setting, but the real performance increase was very small.

Socket 939 Dual-Channel motherboards were found to exhibit a very wide performance difference between a Command Rate setting of 1T and a setting of 2T. The impact on memory bandwidth is dramatic between these 2 settings. In SiSoft Sandra 2004 standard buffered Memory Benchmarks, a 1T command rate showed a Sandra bandwidth of 6000 Mb/sec, while a 2T rate with the same 2 DIMMs in Dual-Channel mode was only 4800 Mb/sec. This is a huge difference in memory bandwidth and the Command Rate setting definitely impacts performance test results on Socket 939 motherboards. All AnandTech benchmarks were run at a Command Rate setting of 1T. This includes all benchmarks that were run in the CPU tests, as all benchmarks were rerun in the CPU tests as soon as we had verified the performance impact of Command Rate settings.