Odd Memory Overclock Results

[sh1ft3d]

I'm somewhat of a newb when it comes to CPU and motherboard chipset overclocking (not a newb to computers, putting them together, or whatnot). Recently put together a Chaintech nForce4 motherboard with cheapo RAM, and knew I wouldn't get much out of overclocking, but thought I'd try anyway. Default setting was 9x 200Mhtz FSB, which put me at 1.8Ghtz (AMD 3000+ S939).

First attempt was FSB at 205, which put me at 9x 205 = 1845Mhtz and everything was all good (CPU temp, ambient temp, everything checked out ok). Memory was clocked at 418Mhtz (PC3200)... not sure how that got calculated.

So anyway, I got gutsy and pushed FSB to 211Mhtz, which clocked the CPU at 1899Mhtz... and memory to 440Mhtz, and again not sure how that clock on memory was calculated.

When I pushed the FSB to 213Mhtz, that's when my computer basicaly wouldn't start at all, but after a CMOS reset everything is all good now.

My question is, obviously my memory (possibly voltage) held my pc back from being overclocked passed what it did, but how did those memory frequency clock settings get calculated - 418Mhtz w/FSB at 205 and 440Mhtz w/FSB at 211? Any of you savvy overclockers able to explain this mathematical conundrum? Thanks in advance.

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In just two days, tomorrow will be yesterday.

 

[Crashman]

Many boards overclock beyond their setting, it's a good way to cheat in benchmarks. You've seen Tom's complain that some boards run a stock 200MHz bus at an actual 203MHz or more, to gain the advantage in comparisons. Well, it's completely possible that a 205MHz setting is giving you an actual 209MHz, and that a 211MHz setting is giving you an actual 220MHz.

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[sh1ft3d]

That would explain the discrepancies between what CPU-Z reports as far as FSB setting (206.7), and what BIOS reports (207.5)...

So, for AMD64 boards, your memory clock should equal FSBx2? i.e. memory clocked at 440Mhtz is 220Mhtz x 2? ...or memory at 418Mhtz is 209Mhtz x2?

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In just two days, tomorrow will be yesterday.

 

[Crashman]

It IS DDR memory, a base setting of 200MHz whith the memory at 1:1 and a HyperThreading bus ratio of 5x gives you DDR400 and HT1000 bus (2000 when you count both directions separately and add them).

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[sh1ft3d]

ah that makes sense... my main question was how did they come up with 418Mhtz when I had my FSB set at 207.5, but you answered that with your first question. Thanks for sharing the knowledge. My next AMD rig will definitely be using higher clocked memory for some overclocking. I'm kinda hoping this guy that is looking for a new computer buys from me so I can sell him my PC3200 memory and get some PC4000 memory for myself. What memory do you recommend for modest AMD overclocking?

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In just two days, tomorrow will be yesterday.

 

[Crashman]

I like PC4000, the only PC4000 I've tried with good timings has been Crucial Ballistix.

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<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[sh1ft3d]

FSB-RAM divider and overclock with default vcore

slightly... just slightly over my head. :tongue: What exactly is the FSB-RAM divider and vcore? You're saying overclocking more is possible with the cheapo RAM I have?

I'm at work now, and brain is fried after a long day so maybe this will make more sense after putting some thought into it following some much needed R & R... and by the way, thanks for all the help thus far.

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In just two days, tomorrow will be yesterday.

 

[sh1ft3d]

so vcore is the amount of voltage to the core/CPU... that was really hard to figure out. I guess my only question now is in reference to the RAM divider thingy... I'm guessing that will tune the clock frequency down so I could push the FSB higher thus overclocking the CPU without overclocking the RAM so much, right? I am at least on the right path?

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In just two days, tomorrow will be yesterday.