Searching for the Memory Holy Grail: Part 1
by Wesley Fink on July 27, 2003 11:13 PM EST- Posted in
- Memory
Performance Tests
Double-Sided Memory
| DDR400, 800FSB (200x4) Intel 875 Chipset, 2-7-3-3 Memory Timings OCZ3700 GOLD 256MB DS |
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| 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 |
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| 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 |
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| 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 |
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| 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.
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Anonymous User - Tuesday, July 29, 2003 - link
Wesley Fink - Monday, July 28, 2003 - link
Yes, you read it correctly. the mixed dimms can vary from very large drops - 20 to 27% or so - to very little if any drop for closely matched pairs. Performance seems to fare best when mixed pairs are the same capacities and the same "bank" configuration.ViRGE - Monday, July 28, 2003 - link
Very good article, Wesley, but I'm a bit confused on your mixed vs. matched DIMM comparison. On the 1st configuration, 2x256DS + 2x512DS, the timings look to be the same as in the 1st table on page 4, the DDR 400 numbers. Am I reading this correctly? It seems odd(although believable) that memory bandwidth dropped 25%, even though it stayed as 4 DS DIMMs at the same timings.PrometheusN - Monday, July 28, 2003 - link
Thanks to a reader for pointing out one correction to this article. The Intel White Paper from the 865 chart reverses 1 and 2 memory positions compared to the 875 white paper. While I did not test 865 performance in the review, I did make reference to the White Paper Chart.We can also wonder, with Intel not sanctioning PAT on the 865, exactly how the 865 boards WITH PAT will behave, and if memory on an 865 with PAT changes back to the same as 875.
Anonymous User - Monday, July 28, 2003 - link
You did not close your table on page eight.3 4 DS/td> Dual Channel
Add a < to the "/td>" ;)
Otherwise... Great article, very informing, thanks for taking the time to write this up.
PrometheusN - Monday, July 28, 2003 - link
Single-Sided or Double-Sided IS a functional description - but it normally is also a visual description. BEWARE dimms that skip every other chips on both sides. These have 4 chips on each side, but are functionally Single-Sided.PrometheusN - Monday, July 28, 2003 - link
According to CPU-Z 1.18C, 4 Sticks of ram - single or double - do NOT disable "PAT" on the DFI 875PRO or the Asus P4C800-E. It depends on how the motherboard BIOS handles the 4 Dimms.Wesley Fink
Shalmanese - Monday, July 28, 2003 - link
Nice article but what are the real world consequences of these numbers? When DDR was 1st introduced, we only saw a ~10% peroformance increase from a 100% increase in memory bandwidth so I am thinking that the difference between 2 and 4 banks would be trivial.ghg - Monday, July 28, 2003 - link
Hi PromNice review, as we expected from you 8-).
Using 4 sticks of doublesided OCZ 3700 Gold disables PAT according to CPU-Z 1.18c.
Same behavior when taking 4 sticks of singlesided OCZ 4000 ?
Ciao
Gary
ghg - Monday, July 28, 2003 - link