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OC'ing - Is my ram the bootleneck?


OPTICAL10

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Hi

I'm trying to emulate the tomshardware OC on the Pentium D 805 with W/Cooling but instead of reaching 4.1Ghz I'm only reaching 3,60Ghz with Corsair TwinX 1Gb XMS2 ProDDR2-4300C3 CAS 3-3-3-8 @ 2.2v.

 

Can you tell me if this ram is the bottleneck? Do I double up to 2GB or do I go for the RAM Configurator recommend for my mobo of TWIN2X2048-6400C4?

 

Please bear in mind this ram has to upgrade to a future proof Core 2 Duo 6800 extreme & nVidia Intel 590 SLi mobo next year. With this in mind could I go for Corsair DDR2 1000 as tomshardware recommends or will my mobo not take it?

 

Any help appreciated.

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  • 4 weeks later...

just because 1 chip will acheive and overclock to a certain setting doesnt mean that all chips will be able to make that sort of grade, there are different chips revisions and steppings to take into account and also you may sometimes find that a manufacturer may if they have a short supply in a certain niche market ie 3.2g chips will simply rebadge a 3.6gig as a 3.2 for example. Or during manufacture some chips will simply manufacture better than others. So just because 1 rig will hit certain figures during clocking it doesnt mean that every rig will hit similar figure. Look out in the overclocking forums and try and identify your cpu its revision and stepping, and compare to see if it is an identical chip or something else. find and use cpuid it will help

 

good luck

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HOWEVER, PC4300 is about as low as you want to go with your particular setup. You may well be able to increase the FSB a bit more with faster memory.

 

The Pentium D 805 has a locked 20x multiplier. To get to 4.1GHz, you must increase the 533FSB to an 820FSB (205MHz, quad-pumped). A 205MHz FSB will run 1:1 with memory rated at PC6700. Since there isn't any (there's PC6400, but that's a little too slow), you'd have to go to the next step up at PC8000 to run this way.

 

Multipliers (FSB:Mem) will make your life easier by allowing for slower memory.

 

A 2:1 multiplier will let you run at about PC3200.

A 3:2 multiplier will let you run at about PC4300.

A 5:4 multiplier will let you run at about PC5400.

 

So, to make sure it's not your memory, you need to be running a 3:2 multiplier since you have PC4300 memory. haggisuk99 is correct, however, in that two CPU's off the same wafer will not overclock the same. Much less two CPU's with different steppings, revisions, lots, etc. So, try your best to OC the system, then check the memory subsystem with Memtest86+.

 

PLUR

CK

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I also have tried to build the 850d system similar to what I read about on toms hardware. I have been able to get the cpu to run at 4.3 however, I have not been able to get it to run stable. I have it set at 4.1 I am using the following settings.

 

fsb@821

cpu voltage@ 1.650 volts

 

My ram is Corsair cmx512 5400c4 it was a set of 2 modules. I think I need differnent ram.

Nothing else is set in bios different from stock. The system seems to run stable and works fine for most aplications, but my problem is it runs slower when I try to play games, Fear etc... When I use the task manager, under performance, I see it says I have about 40 mgs free, when I turn off the overclocking it seems like I have almost 500. the only differnce being the overclock. somhow, the settings must be linked. Any suggestions or comments would be greatly apreciated.

 

p.s. just re reading the forum and saw candy kids comments about fsb mem ratio's so mine needs to be set at 5:4 ? whatever that is? anyway, I will go work on it, and hope I havent talked to long orconfused anyone to bad....

Also, all you 805d overclockers, good luck! :)

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A 5:4 will yield something close to PC5400 so yes, that's correct for you.

 

As for the 40 v.s. 500 MB free thing, I don't know. Perhaps with the faster FSB the system is using more memory space instead of virtual memory. You can use the task-manager to look at how much memory each process is using up. Check that.

 

PLUR

CK

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