Searching for the Memory Holy Grail: Part 1
by Wesley Fink on July 27, 2003 11:13 PM EST- Posted in
- Memory
FSB Overclocking with 1, 2, and 4 DIMMs
Since we have established that the best performance at DDR400 or above (1:1) is with four DIMMs, it is natural to ask whether there is a downside to running four DIMMs instead of two or even one DIMM.| Front Side Bus Overclocking Test Setup | ||
| Processor: | Intel Pentium4 3.0C 800FSB Hyperthreading | Intel Pentium4 2.6C 800FSB Hyperthreading |
| Motherboard: | DFI 875PRO Lan Party(875) | Asus P4P800 Deluxe (865) |
| CPU Vcore: | 1.60v | 1.650V |
| Memory: | OCZ3700 GOLD DDR466 | OCZ3700 GOLD DDR466 |
| vDIMM: | 1.70V (MB limited) | 1.85V (MB Limited) |
| Cooling: | Thermalright SLK-900U | CoolerMaster HeatPipe |
| Power Supply: | Vantec 520W | Powmax 400W |
| Pentium4 3.0C 800FSB CPU | Pentium4 2.6C 800FSB CPU | |||||
| # of DS DIMMs: | 1 | 2 | 4 | 1 | 2 | 4 |
| MAXIMUM Stable FSB: | 992 (4x248) CPU Limited |
992 (4x248) CPU Limited |
968 (4x242) | 1048 (4x262) | 1032 (4x258) | 1024 (4x256) |
| SPD or Manual: | SPD | SPD | SPD | SPD | SPD | SPD |
| CAS Latency: | 2.5 | 2.5 | 2.5 | 2.5 | 2.5 | 2.5 |
| RAS to CAS Delay: | 3 | 3 | 3 | 4 | 4 | 4 |
| RAS Precharge: | 7 | 7 | 7 | 7 | 7 | 7 |
| Precharge Delay: | 3 | 3 | 3 | 4 | 4 | 4 |
Despite the slightly lower overclock possible with four DIMMs, the best 1:1 performance is still with four DIMMs. For example, DDR516 using four DIMMs out-performs DDR530 with two DIMMs – since the four DIMMs are about 7% to 10% higher in UNBuffered memory performance.
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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 ;)