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Core2Duo overclocking guide question

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March 23, 2007 4:03:25 AM

In the Core2Duo Overclocking Guide, under Part2. Memory Adjustments, it says:

Quote:
ASUS: Set ‘DRAM Frequency’ to DDR2-533 @266Mhz FSB (1FSB:1RAM operation)


I have an Asus P5B-Deluxe motherboard and Crucial Ballistix DDR2-800 4-4-4-12 memory. Why would I want to reduce it to DDR2-533?

And what does 1FSB:1RAM operation mean? I don't understand. I guess I need things to be broken down barney-style. :lol: 

More about : core2duo overclocking guide question

March 23, 2007 7:51:08 PM

you have ddr2 rame so even at a 1:1 ratio your rame is running twice that so say your fsb is 333 mhz at as ratio of 1 to 1 your rame would be running at 666 i hope that helps
March 23, 2007 9:44:46 PM

I have an E6600 CPU....can you explain it again please? I still don't understand. Thanks.
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March 24, 2007 12:23:31 AM

the 2 in ddr2 witch is the type of ram you have your ram runs at twice the frequency of the fsb so if you have say ddr2 667 ram ok and a fsb speed of 333 mhz then your ram is really running 666 mhz even thow the ratio is 1:1 dose that help???????
March 24, 2007 3:45:09 AM

Ok let me see if I have things right so far.

My E6600 is 266.67 MHz, multiplier x 9, equals 2400 MHz. And my E6600 has a FSB of 1066 MHz.

My Crucial Ballistix is PC2-6400 running at 800 MHz.

My FSB is 400 MHz (half the speed of my RAM).

Correct?

So how can my FSB be 400 MHz (half the speed of my RAM), but also be 1066 MHz (as indicated by my E6600)?

I'm pretty confused on all this stuff. Is there a Barney style thread somewhere that explains all this stuff?
March 24, 2007 5:31:17 AM

If you run the e6600 at stock speed, it runs at 266*9 and the ram will run at 266*2 (not the full 800 mhz it is capabole of)

If you overclock to the full spec of the ram, you run the ram at 400*2 and the CPU at 400*9=3600 (don't even know if that's feasable as I am not familiar with the e6600).
March 24, 2007 6:19:15 AM

mrknowitall, what you said makes sense. But what still does not make sense to me is why I would want to set my DDR2-800 to DDR2-533 (as suggested in the overclocking guide). Why not just leave it at DDR2-800?
March 24, 2007 6:58:38 AM

You say 'why not just leave it at 800' but the question should really be 'why not set some goofy ram multiplier so it will run at 800'

Don't know exactly why, but it's usually suggested that you run it that way (1FSB:1RAM operation). You are certainly welcome to try using some other multiplier for the ram to get it to run at a higher frequency and see for yourself what sort of impact it has on performance.
March 24, 2007 7:23:12 AM

Quote:
mrknowitall, what you said makes sense. But what still does not make sense to me is why I would want to set my DDR2-800 to DDR2-533 (as suggested in the overclocking guide). Why not just leave it at DDR2-800?

I think if you leave your DDR2 running at full speed 800 MHz and increase your FSB to overclock, your DDR2-800 memory may run at DDR2-1066 speed easily. Most of the CAS5 DDR2-800 won't make that far. That's why Wusy overclocking guide suggests that you set your DDR2 speed first to a lower one, even to 533 MHz, then the memory speed will increase or even surpass the 800 MHz a little bit during overclocking and your system can still boot. But I think this is necessary for "aggressive" overclocking only (up to 3.6+ GHz).

With your CAS4 Ballistix memory, you can leave it at default speed 800 MHz if you OC it moderately. Just give it a try and you can find out pretty quickly how far you can go.
March 24, 2007 7:29:34 AM

Ack....sorry....still not sinking in.

Quote:
I think if you leave your DDR2 running at full speed 800 MHz and increase your FSB to overclock, your DDR2-800 memory may run at DDR2-1066 speed easily.


Why would I want my memory to run at DDR2-1066? Isn't that 533 MHz? Even 533 x 7 = 3731 MHz which is way over what I want to run my CPU at.
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March 24, 2007 7:53:54 AM

Does it really matter?

The reason why you would want to run your memory slower initially is to prevent it from messing with your max cpu OC. Keep it within specs, and it wont cause problems. Push it beyond ddr2-800 and it may cause errors. This may give you a false indication that your cpu has reached its limits.
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March 24, 2007 7:55:42 AM

And your cpu speed isnt 533*7, it would be 266*7.
March 24, 2007 7:56:03 AM

Try lowering your Multiplier to 8 and running a 400MHz FSB. 3.2GHz cpu speed with your ram coming in right at the 800MHz speed.
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March 24, 2007 8:06:24 AM

Btw your memory isnt running at 800mhz if you dont OC. Your real FSB when not OCed is 266mhz and your RAM is DDR2 (Double Data Rate) so it runs at 2x your FSB speed which is 533mhz. In order for you to reach your RAMs potential you need a 400mhz FSB (as said before). Setting your RAM to 533mhz (1:1 ratio) is not lowering the speed its just setting it manually to what it should (but may not) be at when set to auto or whatever.

Edit: I meant to reply to bloodandsoil.
March 25, 2007 7:55:20 AM

The answer to your question is this:

The overclocking guide is for overclocking your CPU. NOT YOUR MEMORY. So to set your memory well below spec (and 1;1 ratio) eliminates any possibility of the RAM holding back your overclock.

DDR2 = double Data Rate. So when your ram is running at 533 the "double data rate" makes it "effectively" running at 1066MHz (double the 533) which is a perfect 1:1 ratio with your CPU's FSB. Get it?

If you run DDR800 it is "effectively" running at 1600Mhz and thus actually outpaces your CPU's FSB of 1067MHz, and the memory ends up waiting for the CPU to catch up. You WILL get a performance boost from running DDR800 but it equates to about 1-2% over the 533. So for the people that spent $400 on best DDR1000 ram out there, what did it gain them......almost nothing in real world apps.

Overclocking is the only time the higher end ram pays off. Running stock with higher end memory does virtually nothing. Buying good ram allows you to OC higher without worrying about ram hindering you. Lowering your memory timings will do far more to benifit your performance then running faster ram.
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March 26, 2007 1:22:30 AM

Ah yes I think thats right, methinks I was talking more about DDR not DDR2. I'm still on a socket 939.

The fsb is actually 266mhz for a newer LGA775 board. Its effectively 1066 because its "quad-pumped" (data is sent 4 times per clock).
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March 26, 2007 1:40:43 AM

I did some research, and what you said isnt entirely correct. No current RAM runs at 533mhz, at DDR2 533 (1:1) it runs at 133mhz. Because it's double data rate RAM it effectively operates at 266mhz, but because the memory bus is 2x the actual speed of the memory it can transfer data at twice the speed, making the memory effectively 533mhz. The rating after "DDR2" is the number of data transfers per second, not the actual speed of the memory.
March 26, 2007 2:09:43 AM

Whats the motherboard FSB for a C2D? Its 266MHz(for the E6XXX anyways). Quad pumped for 1066MHz.

When your running stock FSB of 266MHz and use a 2x multiplier for your ram, that equals DDR533. Now, since the memory is transfering data twice on each clock you are effectively at.........2x 533MHz = 1066. ie 1:1 ratio w/ CPU.

Is this not correct?
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March 26, 2007 3:14:55 AM

No the RAM is at 133mhz real, DDR therefore it is 266mhz effective. The data is transferred at twice the rate coz the memory bus is twice the speed of the memory modules which = 533mhz effective. The 1:1 is with the FSB (ie. FSB:D RAM ratio) not the cpu. That is disregarding one of the doubles there but I'm not sure which one. I think its the DDR that is disregarded in that ratio but I'm not sure.

EDIT: Check out the wiki on it:

http://en.wikipedia.org/wiki/DDR2_SDRAM
March 26, 2007 4:18:22 AM

do you have any reliable sources of this information? you do realize that wiki is written by guys like you and me and may not have any more knowledge on this issue than either of us. ie wiki is not reliable. It may be totally correct but the fact remains that wiki is FULL of blatantly WRONG information!!! I really hate when people cite wiki...heehe fail
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March 26, 2007 4:23:32 AM

I realise that, I have used wikipedia before and found it has very different info from other sites. It's just that its always the first thing that comes up when you type something in.
March 26, 2007 5:59:06 PM

Quote:
Ack....sorry....still not sinking in.

Why would I want my memory to run at DDR2-1066? Isn't that 533 MHz? Even 533 x 7 = 3731 MHz which is way over what I want to run my CPU at.

I don't know if you question was answered yet the way you wanted it, but let me try to explain it this way. Your RAM speeds are directly affted by your bus speed and a ratio or multiplier which are used to calculate the final RAM speed. When you overclock, for example your E6600, and increase your bus speed which in turn increases your RAM speed (since it uses the bus speed multiplied by the ratio [1FSB:1RAM that you saw in the guide]). If you increase your bus speed too much without changing your ratio, your RAM will get overclocked too quickly and your PC will not boot BUT you will still have room to over clock your CPU. By setting the ratio LOWER at first, is to make sure your CPU will get the max overclock and it's the CPU that's causing the PC not to boot (i.e. overclocked too much) rather than the RAM. Once you find the max clock speed for your CPU, then try messing with the ratios and see what your RAM can overclock to. Does this help!?!
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March 27, 2007 2:14:26 AM

Well said.
March 27, 2007 2:40:28 AM

Quote:
Ack....sorry....still not sinking in.

Why would I want my memory to run at DDR2-1066? Isn't that 533 MHz? Even 533 x 7 = 3731 MHz which is way over what I want to run my CPU at.

I don't know if you question was answered yet the way you wanted it, but let me try to explain it this way. Your RAM speeds are directly affted by your bus speed and a ratio or multiplier which are used to calculate the final RAM speed. When you overclock, for example your E6600, and increase your bus speed which in turn increases your RAM speed (since it uses the bus speed multiplied by the ratio [1FSB:1RAM that you saw in the guide]). If you increase your bus speed too much without changing your ratio, your RAM will get overclocked too quickly and your PC will not boot BUT you will still have room to over clock your CPU. By setting the ratio LOWER at first, is to make sure your CPU will get the max overclock and it's the CPU that's causing the PC not to boot (i.e. overclocked too much) rather than the RAM. Once you find the max clock speed for your CPU, then try messing with the ratios and see what your RAM can overclock to. Does this help!?!

Ding ding ding. We have a winner folks. The light finally went off in my head. Thanks for that explanation.

What is the stock ratio of the Asus P5B-Deluxe and an E6600? 1:1?
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March 27, 2007 4:16:50 AM

You mean the light went on :lol: 
March 27, 2007 1:25:54 PM

Your E6600 FSB as standard is 266MHz For a projected 1066MHz in other words your projected FSB is 4 times the amount of the real FSB frequency. Most people suggest running at 1:1 ratio because this setting makes the RAM run at the same speed as the FSB so this is useful if you want to OC a chip very high but say if you want to have a small overclock then you could set your E6600 to 300x9 300 being you FSB now we times that FSB by 4 and we get 1200 you can set your ram to 2.66 or whatever the equivalent you bios offers to run 2:3 ratio and you're set.

The 1:1 Ratio is recommended only because it allows for a higher overclock if you can run the memory faster then do so.

Hope This Helps.

Vic.
March 28, 2007 7:46:47 PM

Quote:
You mean the light went on :lol: 

lol :oops: 
Quote:
What is the stock ratio of the Asus P5B-Deluxe and an E6600? 1:1?
Following what Viceras said, take your RAM speed your FSB speed * 4 ( in his example FSB=(300*4)=1200 and your RAM=800) so 800:1200 reduces down to 2:3 (Did I do that right or did I do it backwards?) If you go over 300, say, 320, your final FSB is 1280:800 (reduces down to 5:8. If you don't have that option and if you leave the ratio at 2:3, the your RAM will be overclocked to 853MHz, which it probably will do as well. Come back with some numbers you get and we'll help you out if you get stuck.
March 28, 2007 8:18:42 PM

To go into more detail your E6600 has an actual Front Side Bus of 266MHz This is then multiplied by 4 to give you a projected 1066MHz FSB. Now you have DDR 2 PC6400 (DDR2 800) so if you set the Memory ratio to run synchronously for example (1:1) then your Ram being DDR2 is running at 533MHz, are you following? Bare with me it'll start to make sense as I go along. In my sig I have increased my actual FSB to 333x9 or 2997MHz, now my actual FSB is 333 so we times that by 4 and we get a projected FSB of 1333MHz or there abouts. Now the whole running memory in sync i.e. 1:1 Ratio just means that we can overclock more cheaply I didnt need DDR2 800 to get my chip to 3GHz I could've saved the cash and got the cheaper DDR2 667 but its always nice to have room to play with :twisted: Now if you want to run the memory async (not in sync) then you need to find the best settings for your setup you may try to OC your actual FSB to 300MHzx9 for a projected FSB of 1200MHz and run your memory async at 2:3 Ratio. your memory will be running at spec DDR2 800 or 2.5 times faster than your actual FSB of 300.

Just reread this monster post I hope it helps and makes sense to you ;) 

Vic.
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March 29, 2007 1:57:45 AM

Thats was almost one long sentence lol, but it makes sense to me at least.
March 29, 2007 4:54:29 AM

Quote:
Thats was almost one long sentence lol, but it makes sense to me at least.
lol. I have a question for you guys... I have DDR2-1000 (PC8000) and but when I overclock over 300x9=2700 and set the RAM to 1000MHz, which is its rated speed, I get rounding errors in super pi and i have trouble with memtest. does this mean the RAM is bad though it functions correctly when it's running at ddr2-800? hope that makes sense.
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March 29, 2007 9:03:54 AM

Hold on so youve tried it at DDR2-800? Are you sure you're setting it right when at 1000mhz?
March 29, 2007 4:10:04 PM

Quote:
Hold on so you've tried it at DDR2-800? Are you sure you're setting it right when at 1000mhz?

What other options are there other than CAS, voltage, and speed? I can't think of any. I have Asus P5W DH Deluxe, and after I set the bus speed, i select the RAM speed from a list (it doesn't show ratios; it calculates the different bus speeds and displays those so I select 1000 [make sense?]).
March 29, 2007 8:24:59 PM

What do you guys think?
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March 30, 2007 3:33:03 AM

I get you now, what I should have said was "are you sure you're setting it at 1000mhz" not whatever mumble I said b4. Have you upped your vcore a bit?
March 30, 2007 9:25:26 PM

Quote:
Have you upped your vcore a bit?

I thought I did, but I'll check again. Should 1.4V be enough?
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March 31, 2007 3:10:54 AM

What chip are you running?
April 1, 2007 12:20:37 AM

C2D E6600. I had it set to [auto] but I tried 1.425V and RAM at 2.3V (settings on the package) it still didn't work. I dropped the RAM speed down to 900MHz and it worked fine. Currently I'm at 2.925GHz (325 x 9) with RAM speed at 975MHz everything is ok. But when I set it to 330 x 9 (2.970GHz and RAM at 990MHz) it starts ti fail memtest. I'll try dropping down the RAM spped again to see if it's the RAM and not the CPU. Sound like the RAM to you?
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April 1, 2007 3:27:26 AM

It does yes. Try upping the vdimm a bit, that might make it more stable. You could also try loosening the timings.
April 1, 2007 5:30:56 AM

Quote:
Try upping the vdimm a bit...try loosening the timings.
I'm at 2.3V, i'll try 2.4V. I'm already at 5-5-5-15, seems to be loose already. Think I should go 6-6-6-18?
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April 1, 2007 6:02:36 AM

Is 4-4-4-... default? If so then 5-5-5-15 should be loose enough. If 5-5-5-15 is default then try loosening it a bit more or upping the vdimm. Up the vdimm first so you dont lose performance that you dont need to.
April 4, 2007 10:31:59 PM

Ok, I had some time to mess around with the overclocking, now I'm at 375 x 9 = 3.375GHz. I tried upping to 400 x 9 = 3.6GHz and windows would load and my logon screen would show for a few seconds then give me BSOD. Is this usually caused by a vCore setting? or FSB? or Northbridge? Southbridge? I will try more voltages etc this weekend and let you know...
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April 4, 2007 10:36:08 PM

Post all your voltage settings, and your mobo.
!