changing CPU frequency

January 8, 2008 at 13:15:56
Specs: WinXP, AMD 3500+/4 GB PC3200 DDR

Hey guys. I have a K8T800Pro mbo and PC3200 1GHz memory. The default multiplier setting given my CPU is 200x11 = 2.2 GHz.

My understanding of all of this OC stuff is that I should be able to achieve the same system setup (i.e., no overclocking) by lowering my multiplier to 9, raising my CPU frequency to 250MHz, and lowering my HT to say 600MHz.

I tried doing just that, but no matter what I do, the system will not accept the 250MHz setting for the CPU frequency, though all other changes are taken. The BIOS allows me to enter 250, but CPU-Z reports later that it didn't really set and returning to BIOS reveals the original 200 setting. What gives? Is there some other change I must make?

Thanks a bunch!


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#1
January 8, 2008 at 13:24:26

Update the BIOS to the latest version and try again. Some processors have a locked multiplier as well.

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#2
January 8, 2008 at 14:16:05

A64 systems are totally different than Intel systems. There is no FSB, so by changing the clock settings from 11 x 200 to 9 x 250 you have gained virtually nothing in performance. Not only that, but you've overclocked the RAM, AGP & PCI buses so high that your new settings won't "stick". You have to try an entirely different approach.

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#3
January 8, 2008 at 14:23:20

I had already updated the BIOS to the latest version.

The point of increasing the CPU frequency to 250 was to take advantage of higher speed memory. I wasn't really interested in overclocking, per se. Supposedly, this mobo allows increasing the CPU frequency without changing the frequency at which other PCI, AGP, etc. are run. Perhaps I have that wrong.

I'm rather certain the multiplier is not locked, since I was allowed to change that and since the CPU-Z reported an overall lower clock speed < 2.2 GHz. So, maybe the CPU frequency is somehow locked?


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#4
January 8, 2008 at 14:33:55

You obviously don't understand how things work. The A64 has the memory controller built into the CPU & communicates with the CPU at full processor speed...in the case of your CPU, 2200MHz (11 x 200). The controller then communicates with the RAM at 200MHz for PC3200.

By changing the settings to 9 x 250, the CPU & controller communicate at 2250MHz. But by not adjusting the memory setting, the RAM bus jumps up to 250MHz & *most* PC3200 RAM can't run at that speed. What you would need to do is change the RAM setting to DDR333, then the RAM would run at approx 205MHz. But what would be the point of that? The gain is so minor that it's not worth the effort.

Don't confuse the DDR rating with the actual freq...PC3200 RAM runs at 200MHz, NOT 400MHz.

Long story short...the only way to improve memory performance is to overclock the CPU.


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#5
January 8, 2008 at 14:45:29

Just to add, you need to lock the AGP at 67MHz & the PCI at 33MHz. And all Spread Spectrum settings need to be disabled.

And why would you lower the HT to 600MHz (3x)? Is your board rated for 1000MHz or 800MHz?

Post the make/model of your board. What you listed is the chipset model.


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