1:1 DRAM:fsb ratio...???

[DavidDavisLeeSomething]

Just want to know what the consensus is about the DRAM:fsb ratio.

Been reading that most people think that a 1:1 ratio is the best ideal for overclocking.

That gets me wondering.

I don't know about other's systems but I would have to overclock my FSB to 533 Mhz (100%) just to get a 1:1 ratio....???? That scares me. Or am I not figuring something out right...???

Any help with this would be greatly appreciated.

[Lsdmeasap]

Re: 1:1 DRAM:fsb ratio...???

Yeap, that would be best most would say. Highest FSB you can run is best, but the 1:1 thing is a becoming a myth really. I have seen MANY people test this against multipliers and find that it does not matter much nowadays. You can use a lower Multiplier with 533, such as 7x533 if you do want to run 1:1.

Best thing really for you to do, would be benchmark your system at the above setting for 1:1 against the same speeds using a higher cpu multiplier and a different ram ratio for the same speed and timings. Then you could see for yourself. But below In the second link there is many pages you can see with test comparisions

But, that myth has tested as I said, but is still a Huge discussion at many places and many people do disagree still. But from what I have seen in tests it does not matter, Highest FSB wins no matter the ram multi >>>
RAM 1:1 myth crushed - Computing.Net

The 1:1 myth that just won't die. - EXTREME Overclocking Forums

[mv2devnull]

Re: 1:1 DRAM:fsb ratio...???

I must start by saying that I know nothing, and don't OC. But logically:

* The slowest step in the pipeline is the "bottleneck".
* The pipeline (in Intel pre-Nehalem) is: RAM-MCH-CPU
* The RAM-MCH part depends on the RAM speed
* The MCH-CPU part depends on the FSB
* At 1:1 both parts have the same bandwidth
=> Theoretically, increasing the RAM above that should not help, as FSB is the limit. However, the RAM latencies can change. That is why non-1:1 not only works, but can be more efficient too.

* On OC, you want to crank everything as high as possible, but not all components OC similarly. And not sticking to 1:1 (or any other correlation) may make "most" of each component.

And as said in those linked threads, it is not quite obvious to everybody what numbers you should compare when you ask "Is this 1:1?".


I'd say "whatever works best" is the "ideal" for that set of components&users.

[DavidDavisLeeSomething]

Re: 1:1 DRAM:fsb ratio...???

I couldn't even get my system to boot up with FSB oc'd at 533 Mhz. Had the CPU Multi at lowest to 6x for CPU speed of 3.2Ghz, Memory Multi down as low as as I could get it.

I would guess that the FSB voltage may have been too low anyways. For that FSB speed probably need alot more than +.1v.

I don't know.

I've had more failed/triple reboots/returns to factory default attempts at overclocking than I have had successful ones.

Don't know which of the components might be lagging and/or failing. Memory is brand new Mushkins DDR2 1066 PC2 8500, motherboard rated with support for 1333 Mhz FSB. My weak link is the CPU.

Right now I have my GigaMush system being tested with Orthos. CPU @ 3.2 Ghz, FSB @ 320 Mhz, Memory @ 1066 Mhz, 5:3 DRAM/FSB. Presently it's been running for 55 minutes and everything is OK. Motherboar temp is @ 39c, CPU 50c, Core #1 @ 57c and Core #2 @ 56c.

UPDATE: Ran the Orthos for 2 1/2 hours....no errors. Is it necessary to run it any more???

Different Note:

I did manage a successful overclock that for the very first time took my Memory Write/Copy speeds over 8 Gb/s on the benchmark:

CPU @ 8x @ 3.15 Ghz
FSB@ approx. 350 Mhz
Divider@ approx. 2.4
memory @ 1066 Mhz w/ 6-6-6-21 timings
DRAM/FSB @ 5:6 (nearest to 1:1 that I have ever gotten)

Haven't tested it yet.

Jeesh...another question or 2 just popped into my head:

I can assume that the Read speeds are not as taxing as the Write/Copy speeds....or are they??? My Read speeds were 9+ Gb/s. Like I mentioned above, my Write/Copy were a little over 8 Gb/s. How do I compare all of the Read/Write/Copy speeds with the labled PC2 8500 speeds??

[svcglobal]

Re: 1:1 DRAM:fsb ratio...???

I was able to run @ FSB 380MHz (x 9.5 for CPU @ 3.61GHz) with 2:1 RAM (760MHz) ratio thanks to the DDR3 figures.
Even with high latency, the memory is running fast @ 1520MHz and this give me the best processing bandwidth. I preferred to optimize the OC with focus on memory since this is the slower item of this equation (CPU, MHC, RAM).
Unfortunately, no lucky even with a single MHz increment in FSB - 380MHz is my wall...

[DavidDavisLeeSomething]

Re: 1:1 DRAM:fsb ratio...???

FSB only to 380 Mhz??

How could that be??

I had my fsb up to 444 Mhz.

[Lsdmeasap]

Re: 1:1 DRAM:fsb ratio...???

Ya you may need more FSB voltage for that high of a FSB, and maybe a fan on your NB if temps were high.

You should not for sure have to be using 666 timings though

A 2 hours orthos run is good, but for more trustworthy answer you should run at least 8 or so. Do it while you sleep if you have to. I do 8+ and when I get time 24 to be sure

Your better bet may be to just use the 10 multi and not run 1:1 on your ram, it will be less stressful on your system

As for your speeds, 8500 is the theoretical peak transfer rate for PC28500 Ram, so anything above or below could be normal. Since you are right in that area I would say your ram is fine and it is nothing you should worry to much about. And yes, it does take the ram more time to copy or write data to the chips then it does to read it, so those may often differ because of many factors including the fact that this Data must travel thru the NB to the CPU and back again.

Here is some DDR2 reading, which I am sure you know most of, just thought I would link you to Wiki >>
DDR2 SDRAM - Wikipedia, the free encyclopedia