Asus A8V Discrepancies between BIOs, CPU-Z and A64 tweaker

Discussion in 'CPU, Motherboards and Memory' started by XEyedBear, Jan 9, 2009.

  1. XEyedBear

    XEyedBear Geek Trainee

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    Apologies if this should be in the overclocking forum. I've posted here because mostly my problem is not about overclocking. It's about understanding some BIOS settings.

    I am trying to maximise the performance of my ASUS A8V (Via K8T800 Pro northbridge) plus AMD Athlon 64 socket 939 3700+ San Diego (E6 stepping) CPU. The problem is that I seem to be getting inconsistent BIOS values presented to me by Asus SETUP, CPU-Z (version 1.49) and A64 Tweaker (version 0.60 Beta) and I want to understand why.

    Having set some BIOS values such that the system wouldn't POST I have set everything back to Auto/factory settings, with the exception of Memclock Mode, which I have set to 'Limit'

    Next I have set Memclock to CPU ratio to 1:1 which SETUP says is DDR200. If I set it to 2:1 (DDR400 - which is the memory I have got - I think!) then the system will not complete POST

    With the 1:1 setting and with AI overclocking (in System Frequency/Voltage setting) set to 'adaptive overclocking' and overclocking showing as 3%, the following confusing data is presented:

    A64 tweaker says Memclk frequency = 100 (I am expecting 200)
    Refresh rate (Tref) = 100 MHz; 3.9 usec (I am expecting 200)

    All other A64 outputs are as expected (not ideal, but expected) with the exception of 2T command setting. I have set this in BIOS as 'disabled' but both A64 and CPU-Z show it as 'enabled' and command rate = 2T

    CPU-Z says Core speed = 2266 MHz (expected at 3% o'clock)
    HT = 1029 (expected)
    Bus speed = 206 MHz (exactly expected)
    Multiplier = 11.0 (expected)

    Data from the SPD: max. bandwidth = PC3200 (200 MHz) which is what I expect)
    Memory = Corsair VS512MB400 (which is what I expect)

    CPU-Z Memory tab says: DRAM frequency = 103 MHz (not what I expect) and FSB/DRAM ratio = CPU/22 (which is not what I expect - I expect CPU/11)

    Does all this mean that my memory system is running only at half its rated speed (in which case why can't I set memclock to CPU ratio to 2:1 ?) or is all this explained in some way - which I don't understand - by the fact that I have dual channel memory?

    Any explanation would be most welcome.
  2. oli

    oli Geek Trainee

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    Your memclk frequency is reported at 100MHz because thats the actual clock speed. It effectively becomes 200MHz because its Double Data Rate.

    The ratio thing is also deceptive. For instance my system runs at a FSB to memory bus ratio of 5:4 but Everest reports it as 10:8. This is exactly the same thing just told differently. As with fractions, if you simplify 2/4 you get 1/2 - the same thing. ie in your case 11 is half of 22.

    Your system is probably not running at absolute 1:1 but maybe 10:11 or 9:11 (practically 1:1). Chipset limitations usually mean that you cannot run the memory twice as fast as the cpu. 4:3 is around the limit.

    Don't take this as gospel. Its the way i have come to understand this stuff. If i'm corrected i bow my head and look forward to learning more.

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