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Old 10-16-2004, 12:39 PM   #1 (permalink)
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Question FSB and Memory Frequency in Bios

Hi Folks!

Sorry, I have searched the threads and have not found an answer to this specific situation. Specs:

Asus A7N8X-X Mobo, Phoenix Bios v6.00Pg
Athlon XP 3200
Kingston DDR400 - 1GB
MSI GEForce 4 Ti 4200-VTD8X Video, 128MB
On-Board Sound
Western Digital 80GB HD, Caviar WD800JB
Samsung DVD-ROM
Sony Floppy
Aspire X-Infinity Case
Antec 400w PU

Problem:

CPU and mobo capable of supporting 400FSB, jumper on mobo set correctly, but system defaults to 100mhz memory frequency on boot up, and bios set to 100mhz CPU Ext Freq. So, that tells me that I'm only getting a 200mhz FSB - correct? It is supposed to auto-detect and set the memory frequency to 200 mhz, I thought (manual says this frequency multiplied by 2 equals the FSB speed.

I have manually set the CPU Ext Freq in the Bios to 200, and let everything else go auto, and the system will boot ok. However, it gets unstable and either freezes or crashes when playing a game or other processor-intensive activity.

So, I'm either misunderstanding the settings or setting something wrong. Any help you can provide would be greatly appreciated. Thanks in advance, good people.
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Old 10-16-2004, 01:34 PM   #2 (permalink)
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what is your CPU multiple & vcore set at when CPU ext freq is at 200Mhz? You might have to increase voltage or reduce FSB to get it to run stable. If you have a setting called optimal (or something like this) use it instead of auto
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Old 10-16-2004, 01:34 PM   #3 (permalink)
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The CPU's external clock should be set at 200 Mhz. The multiplier is x11 (default), therefore the CPU's internal clock will become 2.2 Ghz.

200 Mhz x 11 = 2.2 Ghz

Considering that the motherboard supports a 400 Mhz FSB, you will have to underclock your memory module.

The DRAM frequency should be set at 100 Mhz.

100 Mhz x 4 = 400 Mhz (FSB)
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Old 10-16-2004, 01:37 PM   #4 (permalink)
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ag3 why are you multiplying DRAM frequency by 4?
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Old 10-16-2004, 02:09 PM   #5 (permalink)
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You have to consider the dual data rate (DDR).

400 Mhz (DDR) x 2 = 800 Mhz (FSB) or 200 Mhz x 4 = 800 Mhz (FSB)
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Old 10-16-2004, 02:38 PM   #6 (permalink)
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That doesn't seem right to me ag3. on A7N8X-X, DDR memory isn't running at 800Mhz. I think you might be confusing that with quad pumping.
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Old 10-16-2004, 03:00 PM   #7 (permalink)
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I used PC3200 w/ 800 Mhz FSB as an example! In his case, it would be...

200 Mhz (DDR) x 2 = 400 Mhz (FSB) or 100 Mhz x 4 = 400 Mhz (FSB)
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Old 10-16-2004, 03:08 PM   #8 (permalink)
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Shucks, folks, this is a little over my head now. I will check the voltages, ek, and repost, but my recollection is that the vcore voltage is "correct" for the CPU (1.65 I believe). Also, I have set the other options to Optimal or Auto where available. And, there's a setting called "By SPD" which I doi not understand.

I know this is basic, and I apologize, but I do not readily grasp what all of these different options mean, and the mobo manual is less than helpful (they seem to assume you already know - lol). It seems to me though that this should be a relative no-brainer, with no over- or under-clocking of anything required - the mobo supports FSB 400, the CPU supports it, etc.

ag3 - I have read something similar to what you posted above re the memory frequency (100 x 4 = 400fsb). But, the mobo manual states that the CPU external clock and the mem freq entries should be the same. Also, AMD states that the XP 3200 runs at 2.2ghz, but when running the system says 1.09ghz. Oh boy...
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Old 10-16-2004, 03:30 PM   #9 (permalink)
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The external clock and DRAM clock are not always synchronized as the external clock varies between multipliers.

What is your external clock currently set at (ex.: 166 Mhz)?
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Old 10-16-2004, 03:50 PM   #10 (permalink)
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ag3 - the first entry in the advanced chipset portion of the bios is called CPU External Frequency, and it's set to 100mhz. This is where I started when I began to change things. I set it to 200mhz, because in the manual it said the FSB was twice this, and I supposedly have a 400mhz fsb. At the same time, I changed the Memory Frequency entry to "By SPD" per the manual. It booted ok, but then was unstable. Here are the settings now, where it runs fine. My question, which may be eternally stupid, is that it looks like I'm not getting the FSB performance I whould be, unless I am misunderstanding something.

Thanks for your help.

CPU External = 100mhx
CPU Freq Multiple Setting - Auto
CPU Frq Multiple = 11 times
System Performance - Optimal
CPU Interface - Optimal
Memory Frequency = Auto
Resulting Freq = Auto
Memory Timing - Optimal
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