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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42 Comments
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jsalpha2 - Tuesday, July 29, 2003 - link
Pardon me, cause I'm tired. Did the article say if 4x(256) is better or worse than 2x(512). Assuming identicle brand and speed of RAM.I think I heard somewhere to go with just two sticks for better performance. Plus then you have open slots for later.
Question #2 Would 2x(512) of cheaper DDR333 be better than 2x(256) of DDR400?
thanks
Anonymous User - Tuesday, July 29, 2003 - link
Great article, it's just missing latency benchmarks.Anonymous User - Tuesday, July 29, 2003 - link
Ok - pardon the newbie question, but - I'm building a P4c with Asus P4P800 board. I want 1 gig of DDR400 ram - what brand/model number do I buy - ?Thanks for your help.
Anonymous User - Tuesday, July 29, 2003 - link
This is all nice and good, but what does it all mean in the real world, run some benchmarks in these various modes and show us whether we should care about it :) bottom line to me is what it does for the games, if i'm losing/gaining 4 FPS i'm more likely to care about the price differences then memtest.Wesley Fink - Tuesday, July 29, 2003 - link
These are quoted form Intel's White Paper, p.13 "NOTES: Ranks per Dimm (1 Rank is a single-sided DIMM, 2 Ranks is a double-sided DIMM)". The common practice of using higher-density Dimms every other Dimm on both sides (4 chips per side) is FUNCTIONALLY a Single Bank or Single-Sided Dimm.As for confirming that 4 dimms was faster, only the tests on the 3.0 were CPU-limited. We also determined maximum overclock on a 2.4C which was not CPU-Limited. Please check Page 7.
Philippine Mango - Thursday, January 25, 2007 - link
Wrong, you didn't use a 2.4C, you used a 2.6 processor which from what I know doesn't overclock as well as the 2.8C or 2.4C..Anonymous User - Tuesday, July 29, 2003 - link
"...we confirmed that the added memory bandwidth more than makes up for the slightly lower overclock with four double-sided DIMMs"To say you 'confirmed it' is quite a leap indeed... as you notably stated, you were CPU limited in going any higher for 1 and 2 sticks, whereas you clearly reached a blockade with the 4 sticks of memory. It could be that 4 sticks of memory causes a blockade in the chipset performance at some GHz, but with a better CPU you might have gone much higher with the opposing configurations.
-Robert
Anonymous User - Tuesday, July 29, 2003 - link
"If you plan to run DDR400 as your base memory speed with an 800FSB processor, your best memory performance will clearly be with four matched double-sided DIMMs"Can somebody help me to understand this?
I have only heard about 2 matched DIMMs...
Four matched DIMMs is 2 X 2 matched DIMMS?
Thank you very much!
Anonymous User - Tuesday, July 29, 2003 - link
While the article was interesting in that it at least confirmed Intel's white paper, I would be interested in your also testing ECC. I have a machine which does double duty as a backup server (plug the disks in the SCSI port and away it goes!). I am just curious as to the performamce hit when ECC is being used.Anonymous User - Tuesday, July 29, 2003 - link
The writer does not distinguish between DS and double bank module ;)