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#1
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Confused about memory settings......
I have an ABIT AB9 Pro (WiFi) m/b with:
Intel C2D E6600 cpu 2Gb ( 2 x 1Gb) Crucial Ballistix DDR2 (pc2 6400) 800mhz ram What are the best settings to get the best speed from this set-up? I have built many pcs for myself and friends, and have overclocked all of my own pcs, and I've not blown one up yet, but, I always get confused by the memory settings, especially the bit where the memory speed is doubled (DDR2) and is a ratio of the cpu speed? In my current set-up I use a dram setting of 533 which gives me dram clock speed of 400 (800 ddr) but where does the 533 come from? or what is it a reading of or related to?And why in the Crucial memory spec (above) are there two different speeds (6400 and 800)? where does the 6400 fit in? I've got my current pc up to 3200mhz with the current settings (default speed is 9 x 272 = 2400mhz) easily and it whizzes along nicely, but I'm sure I'm not getting the best memory settings, and hence could get more speed.... These are the current settings in my ABIT m/b bios.... ======================== Screen = OC Guru: External clock = 400mhz (options = various) Multiplier = 8 (options = various) CPU speed = (400 x 8) = 3200mhz NB strap cpu as = psb1066 (options =by cpu, psb1066, psb533, psb800) DRAM spec (cpu:dram) = 533 (options = by spd, ddr2 533, ddr2 667, ddr2 800) Est new dram clock = 400mhz (ddr2 – 800) PCI Express clock = 100mhz CPU core Voltages = 1.3250v (options = various 1.3250v) DDR2 voltage = 2.00v Screen = advanced bios features: CPU featu - Thermal control = enabled (options = enable or disable) Limit CPUID maxval = disabled = (for WINXP) CIE function = disabled = (options = auto or disabled) Execute disable bit = enabled (options = enabled or disabled Virtualisation technology = disabled (options = enabled or disabled) E1ST function = disabled (options = enable or disable) Screen = advanced chipset features: Dram timing = by spd (options = by spd or manual) Cas Latency (tcl) = auto (options = auto or 3 to 6) Ras# to Cas delay (tRCD) = auto (options = auto or 1 to 15) RAS# precharge (tRP) = auto (options = auto or 1 to 15) Precharge delay (tRAS = auto (options = auto or 1 to 31) Command rate = auto (options = auto or 2T or 1T) Refresh cycle time (tRFC) = auto (options = auto or 1 to 63) ========================== What memory timings should I use in the advanced chipset bios screen? and what memory settings should I use in the OC Guru screen. Any info / explanations gratefully received, thanx... 8-) |
#2
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Confused about memory settings......
pjgtech wrote:
I have an ABIT AB9 Pro (WiFi) m/b with: Intel C2D E6600 cpu 2Gb ( 2 x 1Gb) Crucial Ballistix DDR2 (pc2 6400) 800mhz ram What are the best settings to get the best speed from this set-up? I have built many pcs for myself and friends, and have overclocked all of my own pcs, and I've not blown one up yet, but, I always get confused by the memory settings, especially the bit where the memory speed is doubled (DDR2) and is a ratio of the cpu speed? In my current set-up I use a dram setting of 533 which gives me dram clock speed of 400 (800 ddr) but where does the 533 come from? or what is it a reading of or related to?And why in the Crucial memory spec (above) are there two different speeds (6400 and 800)? where does the 6400 fit in? I've got my current pc up to 3200mhz with the current settings (default speed is 9 x 272 = 2400mhz) easily and it whizzes along nicely, but I'm sure I'm not getting the best memory settings, and hence could get more speed.... These are the current settings in my ABIT m/b bios.... ======================== Screen = OC Guru: External clock = 400mhz (options = various) Multiplier = 8 (options = various) CPU speed = (400 x 8) = 3200mhz NB strap cpu as = psb1066 (options =by cpu, psb1066, psb533, psb800) DRAM spec (cpu:dram) = 533 (options = by spd, ddr2 533, ddr2 667, ddr2 800) Est new dram clock = 400mhz (ddr2 – 800) PCI Express clock = 100mhz CPU core Voltages = 1.3250v (options = various 1.3250v) DDR2 voltage = 2.00v Screen = advanced bios features: CPU featu - Thermal control = enabled (options = enable or disable) Limit CPUID maxval = disabled = (for WINXP) CIE function = disabled = (options = auto or disabled) Execute disable bit = enabled (options = enabled or disabled Virtualisation technology = disabled (options = enabled or disabled) E1ST function = disabled (options = enable or disable) Screen = advanced chipset features: Dram timing = by spd (options = by spd or manual) Cas Latency (tcl) = auto (options = auto or 3 to 6) Ras# to Cas delay (tRCD) = auto (options = auto or 1 to 15) RAS# precharge (tRP) = auto (options = auto or 1 to 15) Precharge delay (tRAS = auto (options = auto or 1 to 31) Command rate = auto (options = auto or 2T or 1T) Refresh cycle time (tRFC) = auto (options = auto or 1 to 63) ========================== What memory timings should I use in the advanced chipset bios screen? and what memory settings should I use in the OC Guru screen. Any info / explanations gratefully received, thanx... 8-) For the arithmetic, you start with the processor. E6600 2.4GHz core/ FSB1066 / 4MB cache. The front side bus (FSB) on the processor is quad pumped, meaning that four data items are transferred per clock cycle. So the CPU input clock is implied by the FSB value. 1066 ---- = 266MHz CPU input clock 4 The CPU input clock also feeds the memory clock synthesizer. That means, when you overclock the CPU, the memory is overclocked too. Your settings above, say you've set the CPU input clock to 400. To work out the effect this has on the memory subsystem, you use ratios. 400 --- * "DDR2-533 setting" == effectively_a_DDR2-800_setting 266 So, your choice of the DDR2-533 setting, used in conjunction with that particular amount of input clock overclocking, results in the memory running at DDR2-800. Now, the timing values used by the BIOS, might be consistent with the original choice of DDR2-533, which is why you want to correct the timing values manually, if they're tighter than they're supposed to be. In terms of the "DDR" in the memory name, that is dual data rate. It means two data items are transferred per clock cycle. If the memory is referred to as "running at DDR2-800", then we'd know the memory bus clock is 400MHz. That bit of info comes in handy when reading a CPUZ screen, as the memory display may be showing the "clock" value, rather than the "transfer rate". So don't panic if something seems to be off by a factor of 2. I recommend CPUZ, as a quick means in Windows, of verifying your settings. For example, when it is showing you the contents of the memory SPD tables, it will be showing you values for Tcl, Trcd, Trp, and Tras, at certain choices of transfer speed. Those would be the settings you might want to use at your new memory transfer rate of DDR2-800. (It all depends on whether the SPD defines table values at DDR2-800. If it does not, then you'd have to rely on the values announced in the product advertisement, as a source of the correct values.) http://www.cpuid.com/cpuz.php Another way to do it, which won't wear out any brain cells, is to set your system to nominal settings, then use CPUZ to show the currently running timing values. If you left the input clock at 266MHz for FSB1066, giving 2.4GHz core, then go to the memory subsystem and set it to "DDR2-800" setting, and "timing by SPD", then when you visit CPUZ in Windows, the currently running values for Tcl, Trcd, Trp, and Tras, would be the ones to use for later adventures with an effective DDR2-800 operating speed. You can compare that to the information offered in an advertisement. For example, 4-4-4-12 is shown here for the Ballistix at DDR2-800, at a voltage of 2.0V (which is 0.2V above the nominal 1.8V operating voltage). Command rate won't be specified, as that is as much a system issue, as an issue for the stick itself. The parameter order for the 4-4-4-12 is CAS-tRCD-tRP-tRAS in the advert. The BIOS screen is not typically printed in the same order, so be careful. http://www.newegg.com/Product/Produc...82E16820148203 Next, you could go back to your overclock settings. 400MHz CPU input clock, "DDR2-533" memory setting (effectively DDR2-800), then copy Tcl, Trcd, Trp, and Tras manually into the BIOS memory setup, just like you saw them in CPUZ (or the advert). Command rate is a bus loading thing. 2T means the address is passed for two cycles, giving more setup time to the memory. It compensates for the Northbridge not being able to drive heavy loads well. At one time, such a setting was only needed when four sticks were present, and two sticks in dual channel config might have survived with a 1T setting. But with really high effective transfer rate choices for memory, even with two sticks in dual channel, sometimes 2T is needed. Or it could even be, that a chipset only ever operates at 2T, and has no mechanism to report that fact. This might be a parameter I test without booting into Windows, such as testing with memtest86+ from memtest.org or booting a Linux LiveCD such as Knoppix or Ubuntu. You don't want to corrupt your Windows boot disk, by booting with overly optimistic memory settings. Perhaps Command Rate 1T is just too tight. I don't know the right answer to this. A number of the settings could be affected by the "ratio" thing, but some of them might not be as critical as say a memory timing value like Tcl. But you do want to be aware, that the automatic option in the BIOS, may not always work out the correct values for overclocked system components. So the above description, is just a skeleton review of the issue. It would take me a lot of experimentation (and finding a utility better than CPUZ), to do everything just right. So when the memory gets overclocked, the parameters used by the BIOS may not be the correct ones. And this is why overclocking is an empirical exercise, where the operator must always be vigilant for stupid BIOS mistakes or incorrect settings. Each BIOS can be designed differently, and it could be that there is a BIOS out there that uses "real" settings instead of "effective". That is why a copy of a program like CPUZ is so useful, because it can help you understand the things the BIOS does well, and the things the BIOS is clueless about. For example, on my current motherboard and current BIOS revision, my BIOS won't even set the Tcl, Trcd, Trp, and Tras according to the values set in the BIOS screen :-( So double checking, and careful testing with "safe" test cases (memtest86+ or a LiveCD boot disk), before booting into Windows, is always a good idea. You want your system to show it is bootable and not corrupting things, before you boot back into Windows (and use CPUZ for another look). As an overclocker, you should always have a backup of your boot disk available to you. If the boot disk is ever corrupted by one of your experiments, you want to be able to restore it without a lot of work. It doesn't happen as much as it used to, but it can still happen. HTH, Paul |
#3
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Confused about memory settings......
Paul, thanx for all that useful info....
Not sure I understand it all, but most of it is sinking in! What about the pc2 6400 bit in the crucial ballistix spec for these memory sticks, where does the 6400 bit come from? Also, I have the pc set up (in the bios) as 8 x 400 giving me 3200 cpu speed, but cpuz shows the cpu speed as 3600? (with 450 x 8 figures) The pc still works ok though. Also, to measure temperatures, i use the bios info, and core clock, and speedfan and an nvidia utility and they all seem to show different cpu, m/b, gfx card and case temperatures, so I'm never sure which one to believe? Is there one utility you would recommend. Thanx again for the info... 8-) |
#4
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Confused about memory settings......
Screen = advanced bios features: CPU featu - Thermal control = enabled (options = enable or disable) Limit CPUID maxval = disabled = (for WINXP) CIE function = disabled = (options = auto or disabled) Execute disable bit = enabled (options = enabled or disabled Virtualisation technology = disabled (options = enabled or disabled) E1ST function = disabled (options = enable or disable) Paul, sorry forgot to add, I presume that I'm correct in disabling most of the cpu throttling stuff on the above bios screen, as this just slows things down as far as I know? |
#5
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Confused about memory settings......
pjgtech wrote:
Paul, thanx for all that useful info.... Not sure I understand it all, but most of it is sinking in! What about the pc2 6400 bit in the crucial ballistix spec for these memory sticks, where does the 6400 bit come from? Also, I have the pc set up (in the bios) as 8 x 400 giving me 3200 cpu speed, but cpuz shows the cpu speed as 3600? (with 450 x 8 figures) The pc still works ok though. Also, to measure temperatures, i use the bios info, and core clock, and speedfan and an nvidia utility and they all seem to show different cpu, m/b, gfx card and case temperatures, so I'm never sure which one to believe? Is there one utility you would recommend. Thanx again for the info... 8-) DDR2-800 is 400MHz clock times 2 transfers per clock cycle. The 800 is megatransfers per second. The DIMM is 8 bytes wide. Multiply DDR2-800 by 8 to get PC2-6400 in units of megabytes/second. So the memory has 6400MB/sec of transfer bandwidth, based purely on the memory bus limitation. The CPU multiplier can change, if the processor supports EIST and EIST is enabled. AMD has a similar feature in Cool N' Quiet. What should happen, is the frequency should remain fixed, and the multiplier gets changed, as well as the Vcore voltage setting. EIST works in response to computing load, so if Windows is idle, then the multiplier could get cranked down. Disabling EIST in the BIOS, should cause the multiplier to remain at the high value under all circumstances. If EIST is enabled, maybe the multiplier will vary between 6 and 9 or so. So I cannot honestly say where the "450" number has come from. That part doesn't make sense. But the range of multiplier values should be a function of the processor. The processor is nominally 266 * 9 = 2400MHz. Nine would be the highest multiplier supported, as far as I know. So where did the 450 come from, for a clock setting ? Is it bogus or real ? Does other information in the CPUZ output, reflect 400MHz as the BIOS choice, or 450MHz ? For example, the memory would have too high a setting, if 450MHz was the actual input clock choice. The memory would be operating above DDR2-800 effective. Maybe the 450MHz is an estimate of the maximum value ? Paul |
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