AnandTech: Searching for the Memory Holy Grail: Part 1

Performance Tests

Double-Sided Memory

DDR400, 800FSB (200x4) Intel 875 Chipset, 2-7-3-3 Memory Timings OCZ3700 GOLD 256MB DS
Number of DOUBLE-Sided DIMMS	MemTest86 MB/Second	UNBuffered Sandra 2003 Memory Test (MB/Second)	Buffered (Standard) Sandra 2003 Memory Test
1	1671	1790 INT 1837 FLT	2974 INT 2972 FLT
2	2544	2600 INT 2660 FLT	4769 INT 4710 FLT
4	2489	2861 INT 2848 FLT	4714 INT 4693 FLT

DDR466, 932FSB (233x4) Intel 875 Chipset, 2-7-3-3 Memory Timings OCZ3700 GOLD 256MB DS
Number of DOUBLE-Sided DIMMS	MemTest86 MB/Second	UNBuffered Sandra 2003 Memory Test (MB/Second)	Buffered (Standard) Sandra 2003 Memory Test
1	1947	2046 INT 2145 FLT	3447 INT 3456 FLT
2	2964	3192 INT 3247 FLT	5614 INT 5584 FLT
4	2900	3421 INT 3455 FLT	5604 INT 5609 FLT

As you can see from the benchmarks above, SiSoft Sandra UNBuffered is a more sensitive benchmark for determining differences in memory performance than the Standard Buffered test – which can sometimes conceal differences in memory performance with buffering techniques. It also appears to be more sensitive than MemTest86 in determining memory bandwidth. This is particularly clear in the benchmarks for two and four double-sided DIMMs in Dual-Channel mode. Standard buffered benchmarks and MemTest86 show the performances of two and four double-sided Dimms as fairly equal, while UNBuffered benchmarks show that four double-sided DIMMs are about 7 to 10% higher in performance – a significant increase.

Later in the review, you will read confirmation from a respected source that the UNBuffered Memory Test results are a better reflection of what is really happening in memory performance on the 875/865 chipsets when comparing two versus four DIMMs. Therefore, for the remainder of tests, we will only use Sandra UNBuffered Memory Test and MemTest86 for benchmarking.

DDR500, 1000FSB (250x4) Intel 875 Chipset, 2.5-7-4-4 Memory Timings OCZ3700 GOLD 256MB DS
Number of DOUBLE-Sided DIMMS	MemTest86 MB/Second	UNBuffered Sandra 2003 Memory Test
1	1953	2193 INT 2203 FLT
2	2821	3051 INT 3129 FLT
4	2821	3318 INT 3467FLT

Single-Sided Memory

DDR500, 1000FSB (250x4) Intel 875 Chipset, 2.5-7-4-4 Memory Timings OCZ4000 GOLD 256MB SS
Number of SINGLE-Sided DIMMS	MemTest86 MB/Second	UNBuffered Sandra 2003 Memory Test
1	1924	2076 INT 2090 FLT
2	2551	2725 INT 2762 FLT
4	2821	3254 INT 3194FLT

Single-sided modules appear to perform very differently on the Intel 875/865 chipsets than double-sided modules. Both MemTest86 and Sandra UNBuffered Memory Test show that four single-sided DIMMs perform much better than two. The UNBuffered Sandra benchmark shows an improvement of almost 20% in performance when using four Dimms instead of two. This is more than double the UNBuffered Performance improvement in going from two DS DIMMs to four DS DIMMs on the 875/865 chipsets

UNBuffered Memory Performance Summary

Having established that the SiSoft Sandra UNBuffered Memory Test is a sensitive benchmark for measuring performance differences in memory configuration, it is now useful to compare UNBuffered Memory Benchmarks for one, two, and four double-sided and single-sided DIMM modules.

UNBuffered Memory Benchmark 875/865
Number of DIMMS	DDR400/800FSB DOUBLE-SIDED	DDR466/932FSB DOUBLE-SIDED	DDR500/1000FSB DOUBLE-SIDED	DDR500/1000FSB SINGLE-SIDED
1	1790 INT 1837 FLT	2046 INT 2145 FLT	2193 INT 2203 FLT	2076 INT 2090 FLT
2	2600 INT 2660 FLT	3192 INT 3247 FLT	3051 INT 3129 FLT	2725 INT 2762 FLT
4	2861 INT 2848 FLT	3421 INT 3455 FLT	3318 INT 3467FLT	3254 INT 3194FLT

In all cases, on both 865 and 875 chipsets, with both single-sided and double-sided DIMMs, four DIMMs is the best performing memory configuration at DDR400(1:1) or higher speed. This may come as a surprise to many of you looking for memory for your 865/875 motherboard. As expected, two DIMMs in dual-channel memory configuration performed better than a single DIMM in all cases. Beyond this, we see that two double-sided DIMMs perform much better than two single-sided DIMMs, but that four single-sided DIMMs perform almost as well as four double-sided DIMMs.