Memory and CPU timings

Am I correct in thinking that setting the Bios to 133 bus is the same as setting fsb to 266? Also, when my 'puter boots it says the memory is running at 200mhz. Is that correct?

A7N8X
XP 2100+
2x Corsair XMS DDR3200 (slots 2&3)

-- Ah sh*t! sys64738 --
9 answers Last reply
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  1. Yes, the 266 bus runs at 133MHz. NO, your memory is actually running at 100MHz.

    This gets confusing for people. Basically, you see two numbers, the DDR number and the actual MHz. The DDR number is twice as big as the actual frequency.

    By default AMD boards go to 100MHz bus speeds. You have to manually set them to 133MHz, I outlined this in the FAQ at the top of these post.

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  2. LOL, wait, your BIOS is already set to 133MHz bus? Is your memory running FASTER or SLOWER than your bus speed? There should be a multiplier to tell you. By SPD autodetection you BIOS is supposed to be able to set your memory at DDR400, which is 200MHz real frequency, so maybe you do have it set right. Otherwize, 200, if a DDR number, would be the speed for PC1600, which your board is probably compatable with as well. Hmm, do you have a way to check the ratio? CPU:RAM should be 2:3

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  3. On the post screen it says ram is running at 200mhz. Bios says "Resulting frequency 200mhz". My settings are:

    Memory Frequency: 150%
    SDRAM Active Precharge Delay: 4
    SDRAM RAS to CAS Delay: 3
    SDRAM RAS Precharge Delay: 3
    CAS Latency: 2t
    FSB Spread Spectrum: 50%


    -- Ah sh*t! sys64738 --
  4. Hey! I'm a nimble knuckle! :D

    -- Ah sh*t! sys64738 --
  5. Perfect, you're running DDR400, aka PC3200, as you should be. Now try reducing Ras to Cas and Ras Precharge to 2

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  6. I'll give it a shot. I guessed on "SDRAM Active Precharge Delay" because I don't know what the heck it is. I tried to set things to Corsair's recommended settings but that wasn't one of them.

    -- Ah sh*t! sys64738 --
  7. Well, it might be pushing things, but if it causes instability you can always go back.

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  8. Ok, now running at 4-2-2. Everything SEEMS stable. If I run memtest with no errors does that confirm stability?

    -- Ah sh*t! sys64738 --
  9. Usually. Sometimes you have to get the whole system hot to know for certain. If you don't see any memory error crashes (usually a BSOD with a memory location), you're probably OK.

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