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Has anyone here overclocked a (multiplier-locked) Barton 2500+ on KV7? I'd like to push the FSB from 166 to 200 (I have PC3200 memory), but after I do it the system won't boot.
Does it have to do with the core voltage to the CPU? What about the dividers? Do I need to play around with the FSB:RAM:AGP ratio or just leave it alone? Some overclocking guides recommend 1:1 ratio of FSB to RAM (if the mobo and memory support 400MHz). But what about the AGP?
I'm not interested in increasing the FSB above 200, just getting it to 200 since both my memory and mobo are rated to handle 400MHz.
Thank you for your insights!
P.S. I'm using ThermalTake Silent Boost (w/ Arctic Silver 5) to cool the CPU, and I'm not sure it is suitable for overclocking. This hsf is rated to handle up to XP 3200+ but my non-overclocked Barton 2500+ is 47C at idle already...
If you don't have the option to lock the PCI/AGP, the AGP will automatically run at the default (66MHz) when the FSB is set to any of the "standard" bus speeds. By that, I mean 100, 133, 166, or 200MHz. It's the bus speeds in between these settings that can cause problems. If your board officially supports 200MHz (400FSB), the AGP will automatically run at 66MHz when the FSB is set to 200MHz, so you should have nothing to worry about in that respect.
Always try to run the CPU & RAM bus at the same speed...meaning 1:1 ratio
If you're not increasing the CPU voltage, I'd suspect that's why it won't boot at 200MHz. Can you adjust the voltage in the BIOS? Default voltage for your CPU is 1.65v, next time, try the FSB at 200MHz & CPU voltage at 1.75v. If that doesn't work, give 1.80v a whirl. You may even have to go higher. Personally, I don't feel comfortable over 1.85v.
To keep CPU temps as low as possible, you should try to find the lowest voltage that will allow your system to boot & run stable.
Asus A7N8X-X
1800+ @ 8 x 210MHz
512MB PC3200
Asus Ti4800SE 128MB
WinME/WinXP Pro
0 
Jam,
I hate to but in, but...
"It's the bus speeds in between these settings that can cause problems."
I didn't know that. Thanks!
So are you saying the agp bus speed will vary if you're in between stock settings? Hmmm???
TIA!
YO
0
It does on VIA chipset motherboards. However, those are locked on NVidia chipset boards.
"...but in my defense, it was dark, I was drunk, and it was delicious!"
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Hi YO,
I could have sworn we went thru this before?
If you don't have the option to lock the PCI/AGP in the BIOS, it will overclock right along with the FSB. I'm sure you know PCI is designed to run at 33MHz, & AGP is always twice the PCI speed, or 66MHz.
If you know what the PCI divider is, you can figure what your max safe FSB limits are before running into problems. One other thing to note is the max safe PCI speed is considered to be 37.5MHz, beyond that, all bets are off. Some people have no problems exceeding this speed, but as far as I'm concerned, it's not worth the risk.
To figure out what the divider is, you simply take the "base FSB" & divide by 33. For instance, 166/33 = 5.
Now, take that 37.5MHz that I mentioned above & multiply by 5:
37.5 x 5 = 187.5Mhz
So if you start at the base FSB speed of 166MHz & have no option to lock the PCI/AGP, any FSB setting between 166 & 188MHz "should" be safe.
Here's the max safe FSB overclock settings for all the base FSB's:
66/33 = 2 x 37.5 = 75Mhz
100/33 = 3 x 37.5 = 112.5MHz
133/33 = 4 x 37.5 = 150 MHz
166/33 = 5 x 37.5 = 187.5MHz
200/33 = 6 x 37.5 = 225MHz
Asus A7N8X-X
1800+ @ 8 x 210MHz
512MB PC3200
Asus Ti4800SE 128MB
WinME/WinXP Pro
0
Jam,
lol! I mis-understood what you were saying. It was probably a brain fart on my part. I kept thinking about my mobile and how many different FSB's I can run at and was thinking hmmm, 133/166/200, and the AGP bus will still be set at 66mhz? lol! I'm glad you're on this board to keep me straightened out. Thanks!
YO
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YOYO
Your mobile chip is not different than the desktop version as far as what jam was referring to. The PCI and by extension the AGP busses are both connected to the FSB in that they are a divisor of it. Remember, it isn't really 33MHz it is 33.3333333MHz. Multiply that by 3, 4, 5, 6, and you get 100 FSB, 133FSB, 166FSB, and 200FSB. Then either double pump as in AMD or quad pump, as in Intel. AGP works the same. So if you try overclocking a Barton 333 and set the FSB up from 166FSB to 176FSB you have now set your PCI bus at 35MHz. Get the idea. The only difference in the Mobile Athlon is that the multiplier is unlocked so you have more flexibility on the settings. The same rules still apply. Some more expensive boards have more than one frequency generators and you can lock down the AGP bus at the 66MHz regardless of how you set the FSB. These are not the bulk of the MBs around. Even then, not ever owning one of these boards, I am not sure if this also lock the PCI bus. Pushing the PCI bus can cause data corruption.
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