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brucek

Over-clocking Ram

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This may be a strange question :)I'm new to over-clocking (just about to install my first non-stock CPU cooler and give it a go- Q6600, 4GB DDR3-1600 RAM). My research on this topic shows that the RAM frequency divider is usually used to reduce the clock into the RAM to comply with the RAM specs. Is there any gain in using the divider as a multiplier and increasing the clock speed into the RAM if I have adequate margin on the RAM speed above the CPU clock?Thanks, Bruce.

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The quick answer is No. However you can try the experiment yourself. As a bit of background, memory dividers don't divide (reduce) anymore. That was in the old days when ram speed capabilities could not keep up with FSB speeds. Once the ram speed capabilities began to outrun the FSB, the industry got together and stopped letting us turn down (divide) ram speeds. They needed us to buy their speedy ram. The dividers went away. Now all a builder can do is Increase (multiply via a bios function still called "The memory divider") ram speeds. Increasing ram speed does not help performance, however it's fun to play with. Your Q6600/GO target is 3.6Ghz. With that CPU's multi of 9X, a 400Mhz FSB will be required. 9x400=3.6. The ram will be driven at DDR or 2X the FSB. 2x400=800. DDR2=800 was all that was necessary. However as long as you already have 1600Mhz rated ram, ya might as well play a bit. Get yourself setup and run the ram at the system's default 800Mhz. Fly around a bit and get the feel of your new rig. Now, turn up the ram to 1600. Any difference?

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The quick answer is No. However you can try the experiment yourself. As a bit of background, memory dividers don't divide (reduce) anymore. That was in the old days when ram speed capabilities could not keep up with FSB speeds. Once the ram speed capabilities began to outrun the FSB, the industry got together and stopped letting us turn down (divide) ram speeds. They needed us to buy their speedy ram. The dividers went away. Now all a builder can do is Increase (multiply via a bios function still called "The memory divider") ram speeds. Increasing ram speed does not help performance, however it's fun to play with. Your Q6600/GO target is 3.6Ghz. With that CPU's multi of 9X, a 400Mhz FSB will be required. 9x400=3.6. The ram will be driven at DDR or 2X the FSB. 2x400=800. DDR2=800 was all that was necessary. However as long as you already have 1600Mhz rated ram, ya might as well play a bit. Get yourself setup and run the ram at the system's default 800Mhz. Fly around a bit and get the feel of your new rig. Now, turn up the ram to 1600. Any difference?
Thanks Sam- I have DDR3 (X38T chipset).I will try some settings- perhaps if I am not driving the RAM as hard as it's designed for I can tighten up some of the timings.Thanks, Bruce.

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Thanks Sam- I have DDR3 (X38T chipset).I will try some settings- perhaps if I am not driving the RAM as hard as it's designed for I can tighten up some of the timings.Thanks, Bruce.
People have different views about this. There are so many variables that it is difficult to feel confident that the experience of any one individual will be typical. My own experience is slightly different from Sam's, so let me give you a different perspective.I would agree that optimising RAM is unlikely to make a HUGE difference; and it does not seem to make any appreciable improvement to PEAK framerates. But I have found that getting the RAM right has made worthwhile albeit subtle improvements in other areas. The two I have noticed are:(i) for any given situation and framerate, especially when close to the ground, textures seem to snap more quickly to the sharpest resolution; and(ii) in really tough graphical environments, where FSX is struggling (lots of weather, lots of complex scenery, a heavy add-on etc) the tweaked RAM helps lift the MINIMUM framerate, thus ironing out some of the bumps and stutters and improving the overall smoothness of the sim.I'm pretty sure it's not just placebo - but I'm not a statistician and I've only got my eyes and the framerate counter, not a laboratory. Anyway, I definitely would not want to go back to slower RAM.On the other hand, as I said at the outset, my experience may not be typical. With my E8600 on an Asus Rampage Extreme with the FSB at 480MHz, my DDR3-1600 RAM defaulted to something like 900MHz on 9-9-9-24 at Command Rate 2 and Performance Level 9, with Everest reporting latency of something like 75ns (those figures are just from memory: it was something like that) - even though it was rated for higher performance. Having done some reading on this and other forums, I've now set it up for 1600MHz on 7-7-7-20 at Command Rate 1 and Performance Level 7, with Everest reporting latency of about 46ns. That is quite a big jump and whether anything less than that would be worthwhile I cannot really say. It seems unlikely that getting from 800MHz to 1066MHz would make any real difference. But I maintain that a jump from 800MHz to 1600MHz could make a worthwhile difference if your combination of CPU, RAM and motherboard will let you use the optimal Command Rate and Performance Level settings. I think you're right to give it a go. You might end up no better off, but provided you don't over-volt anything you shouldn't end up worse off, and you just might gain that little bit of extra performance that will make FSX more immersive for you.Tim

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People have different views about this. There are so many variables that it is difficult to feel confident that the experience of any one individual will be typical. My own experience is slightly different from Sam's, so let me give you a different perspective.I would agree that optimising RAM is unlikely to make a HUGE difference; and it does not seem to make any appreciable improvement to PEAK framerates. But I have found that getting the RAM right has made worthwhile albeit subtle improvements in other areas. The two I have noticed are:(i) for any given situation and framerate, especially when close to the ground, textures seem to snap more quickly to the sharpest resolution; and(ii) in really tough graphical environments, where FSX is struggling (lots of weather, lots of complex scenery, a heavy add-on etc) the tweaked RAM helps lift the MINIMUM framerate, thus ironing out some of the bumps and stutters and improving the overall smoothness of the sim.I'm pretty sure it's not just placebo - but I'm not a statistician and I've only got my eyes and the framerate counter, not a laboratory. Anyway, I definitely would not want to go back to slower RAM.On the other hand, as I said at the outset, my experience may not be typical. With my E8600 on an Asus Rampage Extreme with the FSB at 480MHz, my DDR3-1600 RAM defaulted to something like 900MHz on 9-9-9-24 at Command Rate 2 and Performance Level 9, with Everest reporting latency of something like 75ns (those figures are just from memory: it was something like that) - even though it was rated for higher performance. Having done some reading on this and other forums, I've now set it up for 1600MHz on 7-7-7-20 at Command Rate 1 and Performance Level 7, with Everest reporting latency of about 46ns. That is quite a big jump and whether anything less than that would be worthwhile I cannot really say. It seems unlikely that getting from 800MHz to 1066MHz would make any real difference. But I maintain that a jump from 800MHz to 1600MHz could make a worthwhile difference if your combination of CPU, RAM and motherboard will let you use the optimal Command Rate and Performance Level settings. I think you're right to give it a go. You might end up no better off, but provided you don't over-volt anything you shouldn't end up worse off, and you just might gain that little bit of extra performance that will make FSX more immersive for you.Tim
Thanks Tim,I'm not sure what "Command Rate 1 and Performance Level 7" are. I assume that "Command Rate 1" is "CL1"?Thanks, Bruce.PS. RAM is Mushkin XP.

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Thanks Tim,I'm not sure what "Command Rate 1 and Performance Level 7" are. I assume that "Command Rate 1" is "CL1"?Thanks, Bruce.PS. RAM is Mushkin XP.
CL - as in tCL - is CAS Latency. This is different from Command Rate.Assuming your BIOS allows you to change them:Command Rate lets you choose between 1T (or 1N) and 2T (or 2N). Choose 1 for best performance; choose 2 for better stability.Performance Level may show in your BIOS under AI Transaction Booster or some other brand name. Choose the lowest number that gives you stable operation.NB: Performance Level (and a number of other RAM settings) can also be changed from within Windows using a freeware application called MemSet.Tim

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These are tweaks to improve the ram buss to system buss (Front side buss) data transfer "latency." The theory is this: If the data bit's wait time (latency) is less before it is able to transfer between the memory buss and the FSB, the system's performance will be improved. All these tweaks are attempting to decrease ram buss > FSB latency. For instance non-tweaked homebuilds run ~ 70ns latency. Increasing ram speed decreases this latency number by ~ 2ns per 100Mhz. Increasing your ram speed from 800 to 1600 will decrease a data bit's wait time (latency) before it can be transferred between the memory buss and the FSB by about 16 x 1 = 16ns. If a builder was at 70ns, the decrease will be to 54ns. That's a ~ 30% decrease in latency. With the other tweaks, we can get latency down to the 45ns range. That's a good 40% decrease in latency. The technical hobbiest will enjoy this level of interaction with computer systems. I sure do. The result of these changes are accurately described as subjective (at Very best). You can get 75% of any proposed memory-tweak improvement just by increasing your ram's speed to its rated 1600. If there's nothing there, attempting to achieve that additional 25% by tweaking all that other stuff might be considered only tech hobbiest funtime . . . and fun it is.

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Thanks Tim,I'm not sure what "Command Rate 1 and Performance Level 7" are. I assume that "Command Rate 1" is "CL1"?Thanks, Bruce.PS. RAM is Mushkin XP.
BruceThere is a method to tuning and that method/settings depends on the ability of the memory product installed, the CPU and its base multiplier, the motherboard in use and the cooling solution for the CPURest assured the result to FSX is only "theory" for people who have never done it correctly and use the right parts LOLThat being said and becasue I am very limited on time, I am going to post quick and dirty numbersIf you are on a DDR3 1600 system and you are using Mushkin DDR3 1600 memory, and, your CPU cooler will allow you to run 9x400FSB @ 1.42-1.46v Vcore you should be able to hit DDR3 1600 7-7-7- 1T at CMD 6 on those Mushkin sticks @ 1.90v DDR Voltage and a CPU STRAP setting of 333This is the memory I assume you have: http://www.newegg.com/Product/Product.aspx...N82E16820146777Like I said these are quick and dirty numbers which I am assuming the memory is the better Mushkin DDR3 1600 product you have the right CPU cooler and motherboard to do this... use at your own risk but these are the right settings if all my assuptions are correct with your hardware.. aND they are assumptions at this point so dont do anything unless you feel comfortable playingand be aware some of these settings may not be available on your motherboard... CPU Ratio Setting: 09.0C1E Support: DisabledCPU TM Function: DisabledMax CPUID Value Limit: DisabledVanderpool Technology: DisabledExecute Disable Bit: DisabledCore Multi-Processing: EnabledCPU Clock Skew: AutoNB Clock Skew: AutoFSB Strap to North Bridge: 333 (check memory speed, may need 400)PCIE Frequency: 100DRAM Frequency: 1600MhzDRAM Command Rate: 1NDRAM Timing Control: ManualCAS# Latency (CL): 7RAS# to CAS# Delay (tRCD): 7RAS# Precharge (tRP): 7Cycle Time (tRAS) 20DRAM Static Read Control: DISABLEDDRAM Dynamic Write Control: AUTODRAM Skew Control: AUTODRAM CMD Skew on Channel A: AutoDRAM CMD Skew on Channel B: AutoAi Clock Twister: LighterAi Transaction Booster: Manual Common Performance Level: 07 .. if stable in the rest of the clock reduce to 6 and retestCPU Voltage: (between 1.42 and 1.46v) lower is betterLoad-Line Calibration: EnabledCPU PLL Voltage: AUTOFSB Termination Voltage: AUTONB GTLVerf: AutoNorth Bridge Voltage: AUTO (may need a touch of voltage depending on chipset) Only if unstable try beween 1.35 and 1.50, lower is better DRAM Voltage: 1.90CPU Spread Spectrum: DisabledPCIE Spread Spectrum: DisabledNorth Bridge Chipset ConfigurationMemory Remap Feature: Enabled <---- For 64bit OS OnlyIf you dont see it listed... leave it on AUTONow do note,.. you can get that DDR3 1600 Mushkin up to DDR3 1800 @ 8-8-8-24 (possibly 1T) and tRD 7 but I would have to walk you through some serious tweaking on the CPU GTL and SKEW to do it and it would require a processor changeWhen you are dealing with DDR3 your best bet is to run a Quad processor (such as a Q9650) that will allow 450MHz and DDR3 memory that runs by default 1800 without clocking which typically requres x48 chipset or higher to do that stable... @ 450x9 thats a 4050MHz quad clock on DDR3 1800 8-8-8. The 9650 will run that with a few tweaksI think a correctly set up 1600 as I posted above is your best bet right nowWhen you get into DDR3 speeds the ratio you are specking of means nothing.. its all bout getting the CPU up as high as possible on the fastest DEFAULT memory speed and the lowest memory timingThe old days of 1:1 and the "ram ratios" are no more

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BruceThere is a method to tuning and that method/settings depends on the ability of the memory product installed, the CPU and its base multiplier, the motherboard in use and the cooling solution for the CPURest assured the result to FSX is only "theory" for people who have never done it correctly and use the right parts LOLThat being said and becasue I am very limited on time, I am going to post quick and dirty numbersIf you are on a DDR3 1600 system and you are using Mushkin DDR3 1600 memory, and, your CPU cooler will allow you to run 9x400FSB @ 1.42-1.46v Vcore you should be able to hit DDR3 1600 7-7-7- 1T at CMD 6 on those Mushkin sticks @ 1.90v DDR Voltage and a CPU STRAP setting of 333This is the memory I assume you have: http://www.newegg.com/Product/Product.aspx...N82E16820146777Like I said these are quick and dirty numbers which I am assuming the memory is the better Mushkin DDR3 1600 product you have the right CPU cooler and motherboard to do this... ......................
Thanks for the great replies everyone.Nick, I will look at my BIOS over the next few days and see whether I feel comfortable with the setting changes that you have. That new cooler has not yet arrived so one thing that I will not be doing yet is running up the clock (and voltage) on the CPU, at least not much :)Yes, you have the correct RAM.Sam, it seems that some homebuilders (like me) can really do a lot more with latency if we try. This is quite exciting.Tim, thanks for the clarity on the memory terms.Thanks, Bruce.

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