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 Post subject: Help overclocking mobile barton 2600
PostPosted: Thu Jan 20, 2005 10:35 am 
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I recently got a XP-M 2600 cpu from a friend and I am trying to acheieve a stable overclock that just doesn't seem to be happening. The cpu is a newer 2600 IQYHA stepping and my mobo is an Epox ep-8rda3+. I am running 1GB of geil pc-3200 ram at a 1:1 ratio with a 220mhz fsb. I am trying to get a stable 220x11= 2.42ghz right now but it keeps failing the prime95 test about 3 hours in. I have tried different voltages and I am trying 1.875v right now as we speak. I ran memtest on the pc for 13 hours straight with no problems at this fsb speed. But for some reason this cpu is still not stable at this speed. It will do 2.4 at 200mhz fsb but not 2.42 at 220. I am using a Thermalright SI-97 heatsink with a 92mm panaflo H1A fan which keeps the cpu around 45C under full load at 1.85v. Can anyone give me any tips or suggestions as to what I should try in order to maybe get it stable? Any help is greatly appreciated.


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 Post subject: Re: Help overclocking mobile barton 2600
PostPosted: Thu Jan 20, 2005 10:59 am 
King of All Voodoo2 Cards
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alex2112 wrote:
It will do 2.4 at 200mhz fsb but not 2.42 at 220.


Looks like you hit the ceiling for that particular piece of sillicon.


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 Post subject:
PostPosted: Thu Jan 20, 2005 11:16 am 
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You really think so? I dunno I just thought it should be able to do it because of the great stepping and all cause I know others get even higher than this no problem with the same cpu. I guess I'm just unlucky.


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 Post subject:
PostPosted: Thu Jan 20, 2005 1:45 pm 
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Settle for the lower fsb (200) at 2.4GHz rather than hitting your head on the wall over 2.42GHz at 220. You'll get more benefit from the clockspeed than the frontside bus on the Barton.

As for the roadblocking, it's likely a combination of Geil (they're hit or miss in my experience) and PC3200. You wouldn't necessarily need to show errors in Memtest for an unstable overclock. I wouldn't advise swapping out RAM though because A) it might not be the problem and B) it wouldn't be worth the cost since you can hit your goal of 2.4GHz, albiet at 200.

EDIT: One more thought. If you haven't done so already (and I suspect you have), lock your AGP/PCI bus.


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 Post subject:
PostPosted: Thu Jan 20, 2005 4:11 pm 
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I was under the impression that the Nforce2 boards have the AGP/PCI lock enabled by default and there is no need to enable it anywhere. I could be wrong though, so how do you enable it?


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 Post subject: Mobile OCing (or OCING in general)
PostPosted: Thu Jan 20, 2005 5:52 pm 
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Mobiles generally are EXCELLENT overclockers. My first question... did you get the 35w chip that has a default 1.45 vcore or did you get the one with the 1.65? I have personally OCed the 1.45 2600 to 2.5 ghz with air cooling. I went nuts and got it up to 2.8 ghz with water cooling.
Go to your bios and check the default v core, and if you have the lower chip, feel free to nudge it up in small 3-5% increments. That should fix stability problems.

If you are very serious about OCing, find the tolerances of your system, and be willing to reset your bios quite a bit.

To find your memory OC tolerance, change your bios to allow the FSB to be different from the memory clock. This is ususally called a divider.

First, modify your memory timings:CAS Latency, RAS/Row Precharge (tRP), RAS-to-CAS Delay (tRCD), Row-active-delay (tRAS). These timings are organized in order of performance effect.

Drive these as low as possible, while still letting the system boot up. CAS, tRP, tRCD. You can relax the tRCD a bit if you wish, it will normally help you get better timings all around. Try for something at least like 2.5-3-3-8 (CAS,tRP,tRCD,tRAS). If you have very quality memory, you might be able to hit 2-2-2-8. Once you find the fastest timing possible, keep the CAS the same, and loosen the other 3 values a bit.

After finding out your best timings, determine you max memory clock. Raise your mem clock while lowering your cpu multiplier to ensure you are only stressing the memory. Raise the mem clock by 2 -3 mhz incriments until you can no longer boot up. Once you reach that value, back off the memory clock 5 mhz or so.

To determine your mobo / FSB limit, return your memory to its standard clock and keep the cpu multiplier low, and the dram divider on. Raise the FSB up in the same manner as you did the mem clock. When you no longer boot, drop the value by 5 mhz.

To determine your CPU limit, return everything to default value and raise the CPU multiplier. Keep in mind that CPU speed = FSB x Multiplier. Raise the CPU total speed by about 10 or 20 mhz incriments while keeping the FSB relatively low to ensure you only stress the CPU. Once you find a maximum value in the same fashion, back off 10 - 50 mhz.

With your 3 tolerances in mind, disable the dram divider, which makes the FSB and the ram synchronize again. Set your FSB to the either your tested mem clock or FSB maximum, whichever is LOWER, then change the multiplier so that your CPU clock is lower than the maximum tested cpu clock.

For instance, your maximum FSB is 220, and Maximum Mem clock is 230. Your maximum CPU clock is 2400. Best performance will be achieved by using FSB 220. Work some math and divide 2400 by 220, to get 10.9. Since you must use a whole or half number for your multiplier, use 11 for the multiplier. Since mult 11 would put the clock speed at 2420, lower the FSB a bit to say, 218. Your overclocked speed will be 11x218 = 2398. Boot up to windows and run a few demanding apps to check for stability. There should be no problems if you followed these steps. If you do have some issues, feel free to knock down the FSB a mhz or two.

Hope this helped.


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