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FSB:DRAM ratio

post #1 of 36
Thread Starter 
Im new here, and I have been reading some info on here for the past two-three days and Im amazed at how much info is one this forum! Its awesome. Anyway, on to my question.

I have been reading a lot about the FSBRAM ratio and Im perplexed. I understand that you can have your memory running at at higher speed than the FSB of the system is actually reading (I may be wrong). But I dont understand how to get the 1:1 or other ratios! I have a Pentium D 920 and an ASUS P5N32-SLI SE Deluxe board, and I have looked all over the BIOS for how to set this ratio. On my board, there is an option where you can either have the overclocking setting linked (the cpu and the memory) or you can manually put the values in. I hope you guys can understand what Im talking about or else Ill have to go into BIOS and figure out the term for these values.

Now Im looking to overlclock my system some more, but I want to do it in the proper fasion. I have messed with overclocking my processor and have gotten it to run close to 3.4 by messing with the cpu setting as I was talking about earlier. But I was trying to figure out how to change that ratio between FSB and RAM. Now I have been messing with the settings to see how to get that multiplier to be what I want, but I dont understand how you guys are changing it. I see it in CPU-Z but thats about it.

If you guys can help me, that would be GREAT!

Thanks,

-Travis
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post #2 of 36
I basically have your same setup... So try this, set the cpu to 1120, then set your Mem setting to 560... The voltage needs to be between 1.365 and 1.375 for the VCore, and leave the VDimm voltage set at Auto. Leave your ram timings alone(if you don't know what I'm talking about, don't worry then)... Get back to me on the results.
    
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post #3 of 36
If you see things like "RAM Limit: (DDR400, DDR 266, DDR 100) in BIOS, those are your dividers.
post #4 of 36
Sounds like you set your dividers on your own. Your BIOS is similar to mine in that respect - You choose your own ratio depending on the speeds you input. Allows you to get some abnormal ratios - I'm running 11:16 =)
EDIT
The ratio is
Bus Speed:Ram Speed.
Stock, you have an Bus Speed of 800. Because intel use 'Quad Pumping', divide this by 4 to get the FSB.
DDR is Dual Data rate - Divide the effective frequency by 2 to get the actual frequency. (The Frequency under the memory tab of CPU-z)
FSB : DRAM = your ratio.
To change this ratio, simply change each value individually - Manually putting the values in.
Take a look in my sig to see how it all adds up.
Hope that helps in anyway shape or form.
~Kahuna
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post #5 of 36
Thread Starter 
Wow! Thanks for the info.

JCB: I will try that, but that sounds a little high on the first number to me (im a noob) but I'll try it anyways. After this post I will try it and get back to you.

If anyone else has info they would like to share, please share it! I need all the help I can get.
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post #6 of 36
remember when I say 1120, the cpu is quad pumped, making the actual fsb 280. Since the ram is set at 560 and it is double pumped, the actual frequency of the ram would be 280, giving you a 1:1 ratio of cpu to Ram...
    
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post #7 of 36
woah, wait a minute dude, stock cooling? Try 1080 for cpu, and 540 for the Mem setting... and cpu volatge (VCore) should be at auto!!!
    
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post #8 of 36
Thread Starter 
Ya, thats why I was questioning why you gave me such a high number.

I tried it though, the 1120, and it booted to windows, but then it crashed.

Another question: above where you put in the cpu clock and the mem clock numbers, above the two, why does it say target mem speed?
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post #9 of 36
I believe preset multipliers from the motherboard. Weird deal. Try the last set of numbers I put on there for you. Remember to set the vcore voltage at auto.
    
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post #10 of 36
Thread Starter 
Ya, i just tried that, and it didnt work. The 1080 and voltage set to auto wouldnt work.

Ok so I have a question. After it would start, I set it to 970 and it it wouldnt start. It started to load windows, but then it stopped. Remember vcore was set to auto as well. I lowered it to 960 and here I am now. Why is this? I believe since the cpu muliplier is 14x then if it was at 970, then wouldnt that be an equivelant to 970 divided by 4 then multiplied by 14 to get the speed in Ghz? And that wuold be close to 3.4 right? Why wont windows start at 970?

Edit: On those setting that I tried, I left the memory to be 667. Do I need to change this?

Also, one quick thing; is my motherboard decent for overclocking?

KAHUNA: Thanks for that info, that clears some of it up. I understand what you mean now by dividing to get the actual FSB and then manually putting in the numbers to get the ratio. Thanks again.
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