Motherboard Clock Ratio
 

I have just built my first computer, and do not know how to set the clock ratio.

The motherboard is a Gigabyte GA-7N400 Pro2 and the CPU is an Athlon 2400+ XP.

Should I set it up at x5 or x18 or somewhere in between? I took a guess and set it at x10 and it works at least, but I would like to ensure this is the max performance.

If you are that unsure around hardware I really *really* suggest you set it to "Auto-detect" if there is an option like that in the BIOS. Then you can experiment with enhanced PCI performance and whatnot.


Håkan

I'm not really sure, perhaps if you posted your question a motherboard forum you might have better luck. Here is just one example of a motherboard forum:

http://www.hardwareanalysis.com/content/forum/12/

On my Soyo motherboard I use the autodetect option in one place. In other places I had to manually set things because my BIOS was slightly too old to know the correct settings. I could have re-flashed the BIOS chip with a newer BIOS that would recognize it but I didn't.

Despite not being sure, I will make a stab at anwering anyway. Not knowing the correct answer for sure has never stopped me. So anway, I am assuming that the clock ratio is probably more or less the same thing as the clock multiplier. The clock multiplier determines the speed of the CPU. I believe that the multiplier probably refers to the speed of the front side bus times the the multiplier. What gets tricky is that I believe that there are two channels in the FSB each running at half of the rated speed for the FSB. If I am not mistaken, if the DRAM clock is set 166 MHz the fsb would be running at 333 MHz. So on a computer with a 333 MHz FSB should the multiplier be multiplied by 166 or 333? I am not sure which. My Athlon XP 2600+ uses a 333 MHz fsb. Your Athon XP 2400 probably uses a slower FSB like 266 MHz or something.

Another setting in the BIOS of some computers is the CPU to PCI divider. That has something to do with how fast the PCI slot runs. I believe that PCI slots are designed to run at 33 MHz.

Another confusing detail of AMD processors such as the AMD XP 2400 is that they do not actually run at 2400 MHz. What the name means it that they perform as well as a comparable Intel processor that runs at that speed. I actually have my AMD XP 2600+ running at 2074 MHz. From what I was told by one knowledgable person that is close to the speed that it should run (but is just a tad slow). Well at least my computer seems to work great and is still running over a year later. At the time I had Red Hat 7.3 installed and it came with a program that said my computer was running at 2074 GHz. I use Red Hat 9 now instead and it does not give that information. I also had a diagnostic program installed under Windows that said my computer was running at 2074 MHz and that the FSB was 333 MHz. You should probably find some program that will give that information to you.

Well, that was my lame attempt to explain something I only half understand. Isn't that what most of us do on this forum? Don't call me if you burn up your CPU or something. Until you are sure it would probably be better to underclock than overclock. One week ago I started a computer repair class. We have not yet learned much. By the end of the semmester I will know how I should have built and configured the computer that I have been using. You can take my comments for what they are worth. Building a computer from scratch and installing Linux and Windows on it was a good learning experience. It works great but I made a few minor mistakes along the way.

P.S. I meant to say that my CPU is running at 2074 MHz nor 2074 GHz.

Phew! I was about to get really jealous there. ;)


Håkan

Thanks Rick,

Your comments kinda half explain the situation - still leaves me wondering what to set the clock ratio at and also the FSB setting in the BIOS?

I'll try some research on the Gigabyte website - although the manual that came with the motherboard was poor - so I am not expecting much on the website!

Go to ask.amd.com, select the Desktop/Server/Workstation Processor link and search for XP specs. Select the first result - "What are the operating specifications (temperature, voltage, frequencies, etc.) of my AMD Athlon™ XP Processor?".

You will get a table of different AMD Athlon XP processors. Check carefully that you're looking at the exact correct model and then apply those settings. It probably operates at 266MHz system bus (a.k.a. FSB) and with a 15x multiplier, but you check for yourself. I do not want to be responsible for any burning CPU's around here! :)

Good luck and I hope you enjoy your new computer.

Håkan

You should set the FSB to 133 and multiplier to AUTO setting. Some motherboard won't boot with the processor multiplier set other than AUTO with Athlon. Anyway it should be 133/15x.

Hey thanks guys! I'm now off to a good start.

Yes - multiplier is auto.
The Clk Ratio - I have the facts from the AMD website.

For the BIOS FSB setting ... when I was reviewing the BIOS options, there was only the option for 100MHz, 133Mhz, 166MHz, 200MHz ... however the motherboard is capable of ..

Model GA-7N400 Pro2
CPU Type Socket A
CPU FSB 400/333/266/200MHz
Chipset nForce2 Ultra400/MCP
Memory type DDR400/333/266
Memory socket DDR*4(Dual channel)

Any idea how to set the BIOS FSB setting?

133MHz using DDR - double data rate - is often referred to as 266MHz, so "133MHz" is probably what you should use. :)

Håkan

Hey great. Thanks for explaining that. I switched it to 133MHz and now it is recognised as a 2400+!

And it also explains the problems that I had when I tried setting it to 200MHz! - Then had to pull out the motherboard battery to reset the bios!

This might be useful, on my computer, this Linux command shows how fast my CPU runs:

/proc/cpuinfo